INDEX 



631 



triangular deltidial plates in, 

 392. 

 development in, 383. 

 dorsal fissure in, 263. 

 eudora, 315. 



Jimbrialus, spinules in, 51. 

 high hinge-area iu, 266. 

 hirtus, compound spines in, Hall 



and Clarke, 68. 

 loop in, 292. 

 macronotus, 385. 

 medialis, 385. 

 mucronatus, spiniform processes in, 



78. 

 niagarensis, 383, 385. 



deltidial plates in, 390. 

 pedicle-opening in, 242. 

 perlamellosus, 383, 385. 



triangular deltidial plates in, 

 392. 

 psendo-deltidium of, 385. 

 pseudolineatus, spinules in, 51. 

 radiatus, 315, 383, 385. 

 beak in, 389. 

 development of deltidial plates 



in, 392. 

 discussion of, 382. 

 setigerus, spinules in, 51. 

 spiniform processes in, 77. 

 spirolophns stage in, 284. 

 sulcatus, 383, 385. 

 teeth in, 252. 

 Spirifera bicostata ? var. petila, 380. 

 radiata, 382. 

 ? waldronensis, 334. 

 Spiriferacea, 283. 

 arms of, 276. 

 brachidium in, 274. 

 SpiriferidiE, 283, 392. 



deltidial plates in, 266. 

 deltidium in, 393. 

 primary lamellae in, 416. 

 Spiriferina, 246, 383, 392. 



pi7!5'u2s,deltidialdevelopmentin,393. 

 triangular deltidial plates in, 

 392. 

 pseudo-deltidium in, 392. 

 rostrata, deltidial development in, 

 393. 

 triangular deltidial plates in, 

 392. 

 spinose spires in, 260. 



Walcotti, deltidial development in, 

 393. 

 triangular deltidial plates in, 

 392. 

 Spirigerella, 246. 

 spirolophus stage, 282, 284. 

 Spirorbis, 254. 



development of, Fewkes, 253. 

 spinuliferus, spinules on tubes of, 

 Nicholson, 45. 

 spondylinm, 257. 

 Spondylus, 70. 



calcifer, absence of spines in old 

 age of, 21. 



spine grovi^th in, 17, 21. 

 compound spines in many species 



of, 68. 

 development of spines in, 14. 

 imperialis, process of spine develop- 

 ment in, 1 2. 

 oldest species of, 23. 

 ostrseiform growth in, 20, 21. 

 Pecten-\ike stage of, 20, 21. 

 phylogeny of, 23. 

 primary series of spines in, 17. 

 princeps, radiating ridge of, 10, 11. 

 prodissoconch of, 20. 



smooth, of highly spinose species 

 of, 18. 

 sponges, hexactinellid, progressive dif- 

 ferentiation of ornament in. Hall, 49. 

 "Waldron, 313. 

 spur, definition of, 9. 



on hind limbs of Echidna and Orni- 

 thorhijnchus, 9, 59. 

 spurs of Python, 10, 39. 



on birds, 9, 58. 

 star-fishes, protective spines in, 56. 



smooth surface in early, 25. 

 Staurocephalus, 155. 

 Staurastrum cuspidatum, spine growth 



from frustule of, 43. 

 Stegosaurus, spines on tail of. Marsh, 54. 

 stimuli, external, from environment, 31, 



32, 34. 

 Stomatopoda, movable ocular segment 



of, 119. 

 Streptis, 245. 

 Streptorhynchus, 231, 245. 



subplanum, 327. 

 Striatopora, 424. 



mural pores in, 427. 



