GENERAL INDEX. 449 



Kadiating canals, their ilevclopmrnt centiifugal, 80. 



Ramification of the trophosome symmetrical and asymmetrical, 67. 



Rapp assumes the difference of position in the reproductive organs as affording an essential distinction 



between the actinozoal and hydrozoal types, 11. 

 Rastrites, a genus of graptolites, 176. 

 " Rattlesnake," voyage of, 17. 



Reichert, his determination of a structureless membrane (stiitzlamelle) in the Hydroida, 228. 

 Respiration in the Hydroida, 134. 

 Retiolites, an anomalous graptolitic form, 177. 



Rhabdophora, name of the extinct group represented by the graptolites, 190. 

 Rhabdopleura, comparison of, with graptolites, 184. 



Rltizogeton fusiformis, supposed conversion of its gonophore into a hydranth, 204. 

 Richter, his views of the structure and affinities of graptolites, 185. 

 Rotch, W. D., his discovery of Cladocoryne, 380. 



Sarcode-layer on free surface of ectoderm. 111. (See Protoplasm.) 



Sars, his revision of the genus Coryne, 242, 265 ; his institution of the genus Perigonimus, 321. 



Sarsia strangulata compared with the male sporosac of Eudendrium, 45. 



Sarsia regarded by Agassiz and Clark as the ultimate form of the planoblast in Syncoryne, 279. 



Savigni, his researches on the compound Ascidians, 9. 



Secretion in the Hydroida, 134. 



Semper, his views as to the body-cavity of the Coelenterata, 193, 7iotc. 



Sensation in the Hydroida, 137. 



Sertularia pumila, ccecal processes from its blastostyle, 54; a cosmopolitan species, 161. 



Sertularia polijzonias, a cosmopolitan species, 161; its great bathymetrical range, 165; cited as fossil 



from the Pleistocene, 173. 

 Sertularia operculata, a cosmopolitan species, 161. 



Sertularina, data for the geographical distribution of the Hydroida hitherto chiefly afforded by them, 159. 

 Sexes in the Hydroida, comparison of, 147 ; announcement by Ehrenberg of differentiated sex in the 



Hydroida, 12, 147 ; recognised by Loven, 147. 

 Sexual differences among hydroid colonies, 62. 

 Siphonophora, Huxley's monograph on, 17; diagnostic characters of, 188; comparison of, with 



Hydroida, 195. 

 Solander and Ellis, their admirable iconography, 7. 

 Somatic fluid in the Hydroida ; currents in it, 130. 

 Spadix, 32 ; occasionally branched, 45. 



Spermatozoa in the Hydroida, their form, 64 ; their development, 65. 

 Spiral zooids of Hydractinia, 221. 

 Sporosac or adelocodouic gonophore, its parts, 32 ; locomotive sporosac in Dicoryne, 31 ; development 



of the sporosac, 74. 

 Statocodium, a provisional genus of Syncorynidae, 279, note. 

 Stauridium, nature of its filiform tentacles, 371. 

 Staler idmm productum, its planoblasts shown by Hincks to be identical in form with those oi Sijacunjite 



eximia, 370. 

 Steenstrup, his enunciation of the law of alternation of generations, 13, 101. 

 Steganophthalmia and Gymnophthalmia, division of medusse into, by Forbes, 14. 

 " Stiitzlamelle" of Reichert, a definite structure, 228. 

 Stylactis, employment of this generic name justified, 303. 

 Surface zone, its hydroid fauna, 166. 

 Succession of zooids in the gonosome, centripetal or centrifugal, 108 ; compared witli the inflorescence of 



plants, 108—109. 

 Syncoryne, provisional and doubtful species of, 284. 

 Syncoryne pukhclla, congenital union of medusa; in, 202; retrograde changes of form in its mcdus;ic, 



203. 



