INDEX 



629 



Saxicava arctica, spines on post-umbonal 

 slope of, 45. 

 young, 20. 



scales, prickly, of horned toad, 9. 

 Scenidium, 238, 256, 395. 

 Schenck, H., stipules functioning as 



thorns in Machcerium, 89. 

 Schizambon, 231, 244. 



typicalis, spinules in, 51. 

 Schizobolus, 231, 244. 

 Schizocrania, 231, 244. 



pedicle-opening in, 241. 

 stages of development in, 265, 266. 

 schizolophus stage, 278. 

 Schizophoria, 245. 

 Schizopoda, 200. 

 Schizotreta, 231. 



pedicle-opening in, 241. 

 similar form in both valves, 236. 

 Schizura, caterpillar of, mimicry in, 



Packard, 62. 



Schizurae, cause of spines in, Packard, 80. 

 Schmidtella, 148. 

 Schmidtia, 142, 143, 144. 

 Mickwitzi, 144. 

 pygidium in, 143. 



Schuchert, C., brachidium in Zygospira, 

 282. 



evolution of Brachiopoda, 30. 

 life history of Protremata, 95. 

 rudimentary teeth inKutorgina, 252. 

 specific differentiation in Stro- 



phomenacea, 96. 

 Scutigera, 214. 

 Scytalocrinns validus, spines on terminal 



sacs of, 45. 



sea-lilies, smooth surface in early, 25. 

 -urchins, minute spines in early 



genera of, 25. 

 Seeley, H. G., spines in male Callichthys, 



59. 

 selection, cannibalistic, Verrill, 57. 



sexual, as affecting growth of 

 antlers in deer, Darwin, 58. 



spines from, 57. 

 Sdenopeltis, U3, 151, 152. 

 Sethastylus dentatus, spines in, 48. 

 shell, larval, of Pelecypoda, 19, 20. 



pear-shaped, of Difflugia pyriformis, 



43. 



spherical, of Difflugia globulosa, 43. 

 shells, discoid, spines in, 48. 



of Brachiopoda and Mollusca, de- 

 velopment of spines in, 13. 

 of Mollusca, spiniform projections 



on, 9. 

 Shipley, A. E., early embryology of 



brachiopods, 246. 

 Shumardia, 133. 

 Sieberella, 245. 

 Simpson, C. T., anchoring spines on 



Unio spinosus, 46. 

 'Siphonotreta, 69, 70, 244. 



unguiculata, spinules in, 51. 

 Smith, S. I, characters in the append- 

 ages of Trinucleus, 225. 

 Solenopleura, 142, 145, 172, 179. 



cephalon in protaspis forms of, 



182. 



early protaspis stage in, 123. 

 eye-line in, 125, 179. 

 eyes in, 126, 180. 

 glabella of larval stages of, 141. 

 Robbi, 171. 



Spencer, H., all motion primarily 

 rhythmic, 67. 

 rhythm, 28. 



summary of the operation of the law 

 of multiplication of effects, 6, 7. 

 Sphcerexochus, 153, 155. 



fourth annulation in, 127. 

 Sphserocoryphe, 155, 156. 

 Sphceropthalmus, 142, 145. 

 spider, Madagascar, mimetic features 



in, Peckham, 61. 

 spiders, mimetic forms of, 61. ., 



spiny, protective mimetic features 



in, 62. 

 spine, definition of, 9. 



development, evidence of old age 

 in, 17. 



in Brachiopoda, 14. 

 in conical non-coiled Gastrop- 

 oda, 14. 



in Mollusca, 14. 

 in Spondylus imperialis, 12. 

 differentiation in Radiolaria, 16, 



69. 



direct and progressive growth of, 10. 

 from frustule of Attheya decora, 

 43. 



of Staurastrum cuspidatum, 43. 



of Xanthidium armatum and 



Anthrodesmus octocornis, 43. 



