INDEX 



627 



protegulnm, 230. 



affinities of, 232. 



modifications in, from acceleration, 

 233. 



smooth, of Brachiopoda, 18. 

 protembryo, 120, 247, 248. 

 Proteus, external limbs in, 76. 

 Protoceras, horns in two sexes of, Marsh, 



58. 

 protoconch, plain, of cephalopod, 18. 



smooth, of Mollusca, 18. 

 Protolenus, 142. 

 Protopeltura, 142, 145. 

 Protoplasta, 43. 

 Protremata, 242, 247, 282. 



decline in, 96. 



defined, 244. 



deltidium in, 257. 



life history of, Schuchert, 95. 



punctate genera of, 260. 

 Protrilobita, Haeckel, 112. 

 Protypus, 142, 145. 

 Pseudocrania, 244. 

 Pseudophillipsia, 148. 

 Pseudosphcerexochus, 155, 156. 

 Psilocephalus, 146. 



position of eyes in, 147. 

 Pterinopecten, 23. 



spondylus, spines in, 51. 

 Pterocephalia, 142. 

 Pterophloios, 284. 



lophophore in, 280, 281. 



ptycholophus stage in, 284. 

 Pterygometopus, 156. 

 Pterygotus, plate-like telson in, 84. 

 Ptychaspis, 142, 145. 

 ptycholophus stage, 280, 284. 

 Ptychometopus, 154. 



glabella in, 154. 



Ptychoparia, 129, 139, 140, 142, 143, 145, 

 172, 176, 179, 180. 



cephalon in, 129. 



protaspis forms of, 182. 



early protaspis stage in, 123. 



eye-line in, 125, 126, 179, 180, 

 223. 



eyes in, 126, 180. 



first protaspis stage in, 139. 



free-cheeks in, 123, 124, 181. 



glabella in, 180, 182. 



in larval, 126, 141. 

 Kingi, 171, 172. 



Linnarssoni, 171. 



young specimen of, Callaway, 



178. 



ontogeny of, 135. 

 protaspis stage in, 136. 

 Ptychopyge, 146. 

 Pygidiata, Haeckel, 1 12. 

 Pygope, 307. 



python, probable origin of vestigial hind 

 legs of, 76. 



reduction of limbs in, caused by 



disuse, 82. 

 spurs on, 10, 39. 



Quenstedt, F. A., classification of trilo- 

 bites, 111. 



R 



radicle, nuculoid, for Aviculidse and 



allied forms, 23. 

 Radiolaria, compound spines in, 68. 



Nasellarian, terminal spine on, 43. 



projecting rays and processes of, 9. 



spine differentiation in, 16, 69. 



spine production in, 13. 



spines in, 48. 



Spumellarian, spines in, 44. 

 Rangifer tarandus, antlers in, 53. 

 Raphiophorus, 138, 220. 

 ratan, leaf of, 89. 



length of stems in, Kerner, 88. 

 rays and processes of Radiolaria, 9. 

 Reed, F. C., direct line from Cyrtome- 



topus, 156. 



reindeer, antlers in, 53. 

 Remopleurides, 142, 143, 144. 



pygidium in, 143. 

 Rensselceria, 246, 291, 305, 306, 411. 



loop in, 281. 



punctate shells in, 411. 

 reproductive divergence, Vernon, 37. 

 reptiles, dinosaurian, great horned 

 forms of, 96. 



spiniferous lines and ridges on, 52. 

 restraint, external, 31, 38, 39. 



of environment, 31. 

 Retaster cribrosus, spines in, 51. 



