INDEX 



Acantharia, composite spine in, 49. 

 Acanthaster Solaris, protective spines in, 



56. 



acanthogeny, 19. 

 Acanthosicyos horrida, cultivation of, 



Henslow, 74. 

 Acanthothyris, 245. 



Doderleini, spines in, 51. 

 spinosa, spines in, 51. 

 Acaste, 129, 156. 



acceleration in Brachiopoda, modifica- 

 tions from, 233. 

 Acerocare, 142, 145. 

 Achatinella, differentiation of, 65. 



variations in, 36, 37. 

 Achatinellae, free variation in, Hyatt 

 and Verrill, 36. 

 specific differentiation in, Hyatt 



and Verrill, 36. 

 Achtheres, variation in anterior antennae 



of, 192. 



Acidaspidaj, 129, 131, 139, 157. 

 defined, 151. 



extremes of spinosity in, 56. 

 lobes in glabella of, 149. 

 Acidaspis, 70, 113, 129, 149, 151, 152, 

 157, 174, 176, 179, 210. 

 accelerated development of spines 



in, 22. 

 eyes in, 126. 



features of dorsal shield of, 182. 

 glabella in larval, 126, 180. 

 high specialization of, 174. 

 no eye-line in, 180. 

 spiniform processes in, 78. 

 third segment in, 127. 

 tuberculata, 173. 

 Acontaspis hastata, multiplication of 



spines in, 69. 

 Acontheus, cephalon in, 182. 



Acrocephalites, 142. 



Acrosoma arcuata, protective mimetic 



features in, 62. 

 Acrothele, 244. 



marginal upper beak in, 236. 



pedicle-opening in, 241. 

 Acrotreta, 244. 



marginal upper beak in, 236. 

 Actinocrinus lobatus, spines in, 51. 



pernodosus, spines in, 51. 

 Actinopeltis, 155, 156. 

 Actinopteria Boydi, spines in, 51. 

 Adouin's law regarding the Articulata, 



83. 

 ^Eglina, 113, 132, 146, 188. 



armata, eyes in, 147. 



free-cheeks in, 117, 118. 



eyes in, 147. 



free-cheeks in, 124. 



princeps, eyes in, 147. 



rediviva, eyes in, 147. 

 Agassiz, A., homologous structures in 

 Echinodermata, 94. 



L., foundation of orders, 242. 

 interpretation of family charac- 

 ters, 290. 



ontogeny a standard of classifica- 

 tion, 120. 

 Aglaspidse, 132. 

 Aglaspis, 132. 

 Agnostidas, 130, 131, 134. 



defined, 135. 



primitive head structure in, 135. 



primitive structure in, 135. 

 Agnostini, 134. 

 Agnostus, 130, 136, 176, 178. 



absence of eyes in, 183. 



Cambrian, 183. 



cephalon in, 127, 128. 



distinct plate in, 134. 



eye-spots lost in, 135. 



free-cheeks in, 124. 



