GENERAL INDEX. 



Abyssal zone, its hydroid fauna, 167. 



Acalephse, North American, illustrated catalogue of, by Alex. Agassiz, 19. 



Acalepha, instituted by Cuvier as a class, 10. 



Acaulis, its supposed free trophosome probably only a detached hydranlh, 68, 378. 



Acaulis primarius, two very distinct forms referred by Stimpson to this species; reasons for rejecting 



this view, 378. 

 Acraspeda and Craspedota, Gegenbaur's division of medusa; into, 16. 

 Acrocyst, 48. 



Actinia compared with Hydra, 194 ; compared with a hydroid medusa, 195. 

 Actinogonium, its embryonal development, 95. 

 Actinula, development through, 90. 



Adelocodonic gonophores, 30 ; gastrovascular canals in, 45 ; their condition in Eudendrium, 45. 

 yEgenidffl, their metamorphosis, 80. 



^ginidan medusa^ produced by budding from a geryonidan, Haeckel's account of, 84. 

 ^gineta cjenimifera, buds occurring in the cavity of its stomach, 84. 

 Africa, South, large proportion of its hydroids identical with British species, 158. 

 Agamic reproduction, 150. 



Agassiz, Alex., his illustrated catalogue of North American Acalephse, 19; observes the development of 

 the egg in Timaformosa and in Mclicerhim campanula, 97 ; his researches on the development 

 of the marginal tentacles in the hydroid meduste, 80, /lote. 

 Agassiz, Prof. L., his contributions to the natural history of the United States, 17 ; he maintains the 

 hydroid nature of the rugose and tabulate corals, 3, note, and 18 ; his comparison of the 

 interseptal chambers of Actinia with the radiating canals of a medusa, 192 ; his dismember- 

 ment of the genus Tubularia, 400. 

 Aglaophenia, a genus specially characteristic of intertropical and warmer temperate seas, 156. 

 Alcyonaria, diagnostic characters of the order, 188. 

 AUiogenesis of Haeckel considered, 106. 

 Alternation of generations, discovered by Chamisso, 10; its law enunciated by Steenstrup, 13 and 101 ; 



accurately interpreted by Carpenter, 101. 

 Amalthaa Januarii, its hydranth the largest and its stem the thickest yet discovered among the Hydroida, 



394. 

 Ancestral type of the Hydroida, 230. 

 Antennvlaria antennina, canalliculation of endoderm in, 125 ; peculiar free bodies occurring in its 



gonangium, 59. 

 Archydra, 230. 



Ascidians, compound, Savigni's researches on, 9. 

 Atractjlis, validity of this name considered, 299. 

 Atrium, 33. 

 Australian province, 162. 



