INDEX 



637 



regressive, 6. 

 restrictions of, 7. 

 tendency of, 6, 

 variations in Achatinella and Allorchestes, 



36, 37. 

 Vella, spiniform branches of, 75. 

 Verneuilina spinulosa, spines in, 44. 

 Vernon, H. M., reproductive divergence, 



37. 

 Verrill, A. E., AchatineUte, 36. 

 cannibalistic selection, 57. 

 characters in appendages of Tri- 



nucleus, 225. 

 importance of tabul£e in a natural 

 classification of corals, 427. 

 vertebrse, spines of, 9. 

 vertebrates, hornless young of horned, 



19. 

 Verwom, development of extinct Ostra- 



coda, 310. 

 vitality, ebbing, Geddes, 12. 



W 



Waagen, W., classification of Brachiop- 

 oda, 242, 290. 



septal and dental plates in the 

 terebratuloids, 297. 

 Wachsrauth, C, and Springer, F., 

 development of tubercles of Crinoidea 

 and Asteroidea into spines, 50. 

 spines on ventral sacs of Crinoidea, 

 45. 

 Walcott, C. D., additional thoracic seg- 

 ments in Triarthrus Becki, 217. 



biramous appendages in Triarthrus, 



200. 

 casts of pedicles of fossil Lingulse 



and Eichwaldia, 257. 

 classification of trilobites, 1 14. 

 development of trilobites, 310. 

 metamorphoses of trilobites, 166. 

 mouth in Calymmene, 209. 

 possible trilobite eggs, 169. 

 young of Olenellus asaphoides, 178. 

 Waldheimia, 411. 

 bicarinata, 413. 

 Mawii, 413. 

 recurved loop in, 413. 

 septigera, 297. 



Wallace, A. R., on the origin of xeroph- 

 ilous plants, 74. 



protective horns in males of Copri- 

 dse and Dynastidse, 60. 

 WhitfieMeUa, absence of embryonal 

 sinus in, 388. 



nitida, 351, 352, 356, 373, 378, 392. 

 discussion of, 374. 



early stages of growth in, 373. 

 tumida, 377. 

 Whitfieldia, 377. 

 WiUiams, H. S., variations in stock of 



Atrypa reticularis, 25. 

 Woodward, H., affinities of trilobites, 

 110. 

 Trilobita the earliest forms of Crus- 

 tacea, 184. 



X 



Xanthidium armatum, spine growth 



from frustule of, 43. 

 Xiphogomium, 148. 

 Xiphosphmra polios, spines in, 48. 

 Xylotrupes gideon, horns in, 60. 



Youngia, 155, 156. 



Zacanthoides, 113, 142, 143, 144. 



pygidium in, 143. 

 Zaphrentis spinulosa, spiuules in, 50. 

 Zellania, 246, 300, 304, 308. 



schizolopbus stage in, 279. 

 Zilla, branches of, transformed into 



spines, 74. 

 Zittel, K. A. von, classification of 

 articulates, 112. 



of Trilobita, 112, 132. 

 historical review of trilobites. 111. 

 oldest species of Spondylus, 23. 

 terminal spine in NaseUarian Eadi- 

 olaria, 43. 

 zoea of common crab, 56. 



of Decapoda, spines in, 57. 

 Zoic maxima, Gratacap, 35. 

 zugolophus stage, 281, 284. 



