CONTRIBUTIONS

to

THE NATURAL HISTORY

of the
  
  UNITED STATES OF AMERICA

by

LOUIS AGASSIZ

Second Monograph

In Five Parts. - I. Acalephs in General. - II. Ctenophorae. - III. Discophorae. - IV. Hydroidae. - V. Homologies of the Radiata.

With Forty-Six Plates

Volume IV

BOSTON:
LITTLE, BROWN AND COMPANY.
LONDON:
TRÜBNER & CO
.

1862.

380 + 18 pages with  18  plates and 50 woodcuts.

This electronic edition prepared by Dr. David C. Bossard
from original documents in the library holdings of
Dartmouth College, Hanover New Hampshire.

December, 2005.

Copyright © 2005 by David C. Bossard.

NOTE: If the woodcut legends are too small to read easily, you may view high resolution (400ppi) images at text-figures. These images are listed by page number and figure number.

VOLUME IV

CONTENTS.

PART III.

DISCOPHORAE



CHAPTER I.

DISCOPHORAE IN GENERAL

SECTION 1. Structure of the Discophorae. 
003  004  005  006
Natural Limits of the order. Discophorae phanerocarpae Esch., Steganophthalmata Forbes, Aeraspeda Gegenb. p. 3-6.

SECTION 2. Sub-orders of the discophorae proper.  007  008  009
Their limitation. How families differ from sub-orders. Rhizostomeae, Semoeastomeae, Haplostomeae. p. 7-9.


CHAPTER II.

THE GENUS AURELIA AND ITS SPECIES.

SECTION 1. General remarks. 
010  011  012
Different modes of study and sub-divisions of our science. p. 10-12.

SECTION 2. Formation and growth of Aurelia flavidula, including comparisons with Cyanea aretica.  012  013  014  015  016  017  018  019  020  021  022  023  024  025  026  027  028  029  030  031  032  033  034  035  036  037  038  039  040  041  042  043  044  045  046  047  048  049  050  051
The egg of Aurelia flavidula. The planula of Aurelia flavidula. The egg of Cyanea aretica. The planula of Cyanea artica. The scyphostoma of Aurelia and Cyanea. Histology of the scyphostoma. The strobila of Aurelia. The ephyra of Aurelia. Structure of the eye, by Prof. H.J. Clark. The lasso-cells and their special structure. p. 12-51.

SECTION 3. Structure of the adult Aurelia flavidula.  051  052  053  054  055  056  057  058  059  060  061  062  063
Symmetry of the body. Primary number of identical segments. Ambulaeral and interambulaeral systems. The young and the adult. Compared to Echinoderms. p. 51-63.

SECTION 4. Homological relations of Aurelia and Echinoderms.  063  064  065  066  067  068  069  070  071  072
The Coelenterata and Echinodermata built upon the same plan. Arrangement of their spheromeres. Comparision of Aurelia with Echinarachnius. The radiating tubes of the Acalephs and Echinoderms. p. 63-72.

SECTION 5. Closer affinities of Aurelia.  072  073  074  075
Resemblance between the younbg and the Aeginidae, while the adult approximates the Rhizostomeae. p. 72-75.

SECTION 6. Habits of Aurelia.  075  076  077  078
Its appearance in the spring and disappearance in the autumn; passes the winter in a larval condition. p. 75-78.

SECTION 7. Nomenclature of Aurelia.  078  079
The young and the adult, in various states of preservation, referred to many genera, supposed to be distinct, but all of which must now be suppressed. p. 78-79.

SECTION 8. Peculiarities of the Aurelidae as a family.  080
Its special pattern. p. 80.

SECTION 9. Generic characters of Aurelia, and specific characters of the Aurelia flavidula of North America.  081  082  083  084  085  086
Comparison with the European Aurelia nurita. Enumeration of the species of this genus. p. 81-86.


CHAPTER III.

THE GENUS CYANEA AND ALLIED GENERA.


SECTION 1. General description of Cyanea artica.  087  088  089  090
Difficulties in describing Acalephs. Misuse of names to designate their parts. p. 87-90.


SECTION 2. The abactinal system of Cyanea.  091  092  093  094  095
Imperfection of older illustrations. Structure and appearances. p. 91-95.
 
SECTION 3. The lower floor of Cyanea, and its connection with the upper floor.  095  096  097  098  099  100  101  102  103  104  105  106  107  108
Actinal system. Homology of the parts. Essential elements of the structure of Cyanea. Large amount of structural water in Acalephs. Broad and narrow pouches alternating. Concentric and radiating folds. Tentacles. Genital pouches..Complicated structure of the actinostome. Effects of sections upon living Medusae. p. 95-108.

SECTION 4. Growth of Cyanea.  109  110  111  112
The young compared to adults of different species. p. 109-112.

SECTION 5. Histology of Cyanea.  112  113  114
The actinostome and the tentacles. p. 112-114.

SECTION 6. Cyaneidae as a family.  114  115
Their form exhibits a peculiar pattern. p. 114-115.

SECTION 7. The genus Cyanea compared with other genera.  115  116  117  118  119
Phacellophora and Heccaedeconima. Sthenonia. Stenopytycha. Chrysaora. Couthonyia. Medora. Patera. Donacostoma. Pelagia. p. 115-119.

SECTION 8. The Species of Cyanea compared with one another.  119  120
Cyanea arctica, fulva and versicolor. Cyanea capillata and Lamarckii. Cyanea Postelsii and ferruginea. p. 119-120.


CHAPTER IV.

THE GENUS PELAGIA AND ALLIED GENERA.



SECTION 1. The family of Pelagidae.  121  122  123  124
Its characters. Nausithoe probably the young of Pelagia. p. 121-124.

SECTION 2. The genera of Pelagidae.  124  125  126  127
Pelagia. Placois. Chrysaora. Dactylometra. Polybostrycha. Melanaster. Zygonema. p. 124-127.


SECTION 1. Description of Pelagia cyanella.  128  129  130
Direct development from the egg: the embryo assumes the form of an ephyra, without ever passing through the strobila state characteristic of aurelia. Comparison of the young with Nausithoe. p. 128-130.


CHAPTER V.

THE DISCOPHORAE RHIZOSTOMEAE


SECTION 1. The Rhizostomeae in general.  131  132  133  134  135  136  137
Structural peculiarities. Polystomy. Constitute a distinct sub-order, with many families. p. 131-137.

SECTION 2. The genus Stomolophus.  138
Comparison with Rhizostoma. p. 138.

SECTION 3. The genus Polyclonia.  139  140  141  142  143  144  145  146  147  148
Founded upon Medusa frondosa Pall., recently obsered in Florida. Its peculiar habits; gropes in the mud, and is seldom seen floating in the water. Polyclonidae as a family. Generic characters. p. 139-148.


CHAPTER VI.

ENUMERATION AND GEOGRAPHICAL DISTRIBUTION OF THE DISCOPHORAE

SECTION 1. Tabular view of the discophora known at present.  149  150  151  152  153  154  155  156  157  158  159  160  161  162  163  164  165  166  167  168  169  170  171  172  173  174  175  176
They form three sub-orders, with fifteen families. p. 149-176.

SECTION 2. Geographical distribution of the Discophorae.  177  178  179  180
The lower types are the most widely distributed. Distinct Acalephian Faunae. p. 177-180.



PART IV. - HYDROIDAE

CHAPTER I.


CORYNE AND ALLIED MEDUSAE

SECTION 1. General remarks upon the Hydroids and naked-eyed Medusae.  183  184  185
Hydra and Medusa Form. Bibliography.  p., 183-185.

SECTION 2. The Hydroid form of Coryne mirabilis.  185  186  187  188  189  190
The hydrarium and its structure.  p. 185-190.

SECTION 3. The reproduction of coryne mirabilis.  190  191  192  193  194  195  196  197  198  199  200  201  202  203  204
The budding of Hydroids and Medusae. p. 190-204.

SECTION 4. Histology of Coryne mirabilis.  204  205  206  207  208  209  210  211
The adult Hydroid. The Medusae-buds. The structure of the egg. p. 204-211.

SECTION 5. Adult Medusa of Coryne (Sarsia) mirabilis.  212  213  214  215  216  217
Its form varying extensively, its habits and voracious dispositions, its quick motions, its structure. Anomaly in the number of spheromeres and bearing of these variations upon specific distinctions. Family affinities of the Hydroids and Medusae. The Hydroids of the same family bear similar relations to one another as the free Medusa. p. 211-217.


CHAPTER II.

THE GENERA CLAVA AND RHIZOGETON

SECTION 1. The adult Hydroid of Clava leptostyla.  218  219  220
Bibliography. Structure. p. 218-220.

SECTION 2. The medusoid buds of Clava leptostyla.  221  222
They are the simplest among the Tubularians, and never appear as independent Medusae. p. 221-222.

SECTION 3. Embryology of Clava leptostyla.  222  223  224
It produces planulae. p. 222-224.

SECTION 4. Rhizogeton fusiformis.  224  225  226
The adult hydromedusarium. The Hydroids. The Medusae-buds. Transformation of the Medusae-buds into Hydroids. p. 224-226.


CHAPTER III.

THE GENERA HYDRACTINIA AND HALOCHARIS

SECTION 1. The hydroid form of Hydractinia polyclina.  227  228  229  230  231  232  233  234  235
Bibliography. Polymorphism. The fretile Hydroid. The sterile Hydroid. p. 227-235.

SECTION 2. Reproduction of Hydractinia polyclina.  235  236
The Hydroid. The Medusoid. p. 235-236.

SECTION 3. Histology of Hydractinia.  236  237  238  239
The Hydroid, the lasso-cells. The horny basis. The egg. The spermatic particles. p. 236-239.

SECTION 4. Halocharis spiralis.  239  240
Proles hydroidea. Histology. p. 239-240.


CHAPTER IV.

THE FAMILY OF TUBULARIDAE

SECTION 1. General remarks upon the Tubularians.  241  242  243 
Bibliography. The family of Tubularidae circumscribed within its natural limits. p. 241-243.

SECTION 2. Hyboeodon prolifer.  243  244  245  246  247  248  249
Adult hydroid. Proles medusoidea. Embryology. Histology. p. 243-249.
-- Since this chapter was printed, I have ascertained that Euphysa belongs to the cycle of Hoboeodon; but it remains to be seen whether the Medusa, here described as Hybocodon, is transformed into a genuine Euphysa, or the Euphysa produced from the tentacular buds of a Hyboeodon.

SECTION 3. Parypha crocea.  249  250  251  252  253  254  255  256  257  258  259  260  261  262  263  264  265
Adult Hydroid and adult Medusoid. Embryology. development of the hydra. Germ-basis.. Medusae-buds. Histology. p. 249-265.

SECTION 4. Tubularia Canthanyi.  266  267  268  269  270  271
Adult Hydroid. Full-grown Medusoid. Embryology. Histology. p. 266-271.

SECTION 5. Thaumocnidia spectabilis.  271  272  273  274  275  276
Adult Hydroid. Full-grown Medusoid. Embryology. Thammocnidia tenella. p. 271-276.

SECTION 6. Corymorpha pendula.  276  277  278
The Hydroid. The Medusae-buds. p. 276-278,


CHAPTER V.

THE GENUS EUDENDRIUM OF EHRENBERG.

SECTION 1. Remarks on the Hydroids referred to the genus Eudendrium, and ther free Medusae.  282  283  284  285
Bibliography. The Hydroids of this type belong to three different families. p. 282-285.

SECTION 2. Eudendrium dispar.  285  286  287  288  289
The Hydroid and the Medusoid. p. 285-289.

SECTION 3. Bougaincillia superciliaris.  289  290  291
The Hydroid, the Medusae-bud, and the free Medusa. p. 289-291.



CHAPTER VI.

THE DORALLARIA TABULATA AS HYDROIDS.

SECTION 1. Millepora alcicornis.  292  293  294  295
Its Hydra. There are twokinds of them, large and small ones. They have no special affinity to the class of Polyps. The Coral stock. p. 292-295.

SECTION 2. Pocillopora damicornis.  295  296
The Coral-stock has the same structure as Millepora. p. 295-296.

SECTION 3. Scriatopora subulata.  296
Affinities to the Corallaria Rugosa. p. 296.



CHAPTER VII.

THE GENERA OF THE CAMPANULARIANS.

SECTION 1. Clytia (Orthopyxis) poterium.  297  298  299  300  301  302  303  304
Bibliography. Adult Hydroid. Embryology. p. 297-304.

SECTION 2. Clytia (Trochopyxis) bicophora.  304  305  306
Adult Hydroid. Embryology. p. 304-306.

SECTION 3. Clytia (Platypyxis) cylindrica.  306  307  308
Free Medusa. Hydroid. The Campanularians embrace Acalephs of different families. p. 306-308.

SECTION 4. Tiaropsis diademata.  308  309  310  311
Free Medusa. Embryology. Order of succession of the tentacles p. 308-311.

SECTION 5. Laomedea amphora.  311  312  313  314  315
Adult Hydroid,  No free Medusa. Embryology. p. 311-315

SECTION 6. Obelia commissuralis.  315  316  317  318  319  320  321
Péron's genus Obelia. Adult Hydroid. Embryology. Free Medusa. p. 315-321.

SECTION 7. Eucope diaphana.  322  323  324  325
Adult Hydroid and its affinities. Embryology. Free Medusa. p. 322-325.

SECTION Dynamena pumila.  326  327  328  329  330  331  332
Bibliography. Structure of the adult Hydroid. Adult Medusoid. Embryology. Budding. p. 326-332.


CHAPTER VIII.

THE GENUS EUDENDRIUM OF EHRENBERG.

SECTION 1. Siphonophorae in general.  333  334  335
Ought to be subdivided into separate sub-orders. p. 333-335.

SECTION 2. The genus Physalia.  335  336
Its polymorphism and special characters. p. 335-336.


CHAPTER IX.

CLASSIFICATION OF THE HYDROIDAE.

SECTION 1. Tabular view of the whole order of Hydroidae.  337  338  339  340  341  342  343  344  345  346  347  348  349  350  351  352  353  354  355  356  357  358  359  360  361  362  363  364  365  366  367  368  369  370  371
It embraces eight sub-orders, with forty-six families. p. 337-371.

SECTION 2. Geographical distribution of the Hydroidae.  371
Location of these Acalephs. p. 371.


PART V. - HOMOLOGIES OF THE RADIATA.

SECTION 1. General Homologies.  375  376
Normal position and natural attitudes to be distinguished. Plan of structure. Spheromeres. p. 375-376.

SECTION 2. Special Homologies of the Classes.  377  378  379  380
Correspondence between the structure of Polyps and that of the Acalephs and Echinoderms. p. 377-380.




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