626 



INDEX 



development of, 422. 

 initial cell in, 426. 

 non-tabulate feature of, 427. 

 normal and abnormal growths 



in, 424. 

 simple cell growth and multi- 

 plication in, 429. 

 mural pores in, 427. 

 prohlematicum, casts of, 426. 

 initial pores in, 426. 

 Pleurostomella altcrnans, single spine in, 



44. 

 plum, loss of spines of, by cultivation, 

 74. 

 spiniform branches of neglected, 75. 

 Plutonides, 142. 

 Podocyrtis Schomburgki, terminal spine 



in, 44. 

 Poli/morphina Orbignii, compound spines 

 in, 68. 



sororia, var. cuspidata, single spine 

 in, 44. 

 Polyzoa, 252. 

 Poramhoniles, 245. 

 porcupine, extreme spinosity in, 70. 

 -men, 92. 



modified hairs of, 9. 

 protection of, by spines, 54. 

 Porifera, nmral pores in, 76. 

 Poulton, E. B., mimetic features in early 



thorn moth, 62. 

 praemagadiform stage, 292. 

 pressure, results of, on an organism, 



Paget, 28. 

 Presticichia, tail spine in, 84. 

 prickle, definition of, 9. 

 prickles on climbing plants, 90. 



on rose and barberry, 9. 

 Prionopeltis, 148. 

 eyes in, 148. 

 fixed-cheeks in, 148. 

 Pritchard, A., spine growth in Arthro- 



desmus octocornis, 43. 

 Prohosciddla, 245. 



difference in valves in, 237. 

 Proceratopyge, 142, 145. 

 Pi-ocervulus, antlers in both sexes of, 57. 

 processes on Echinoderraata, 9. 



spinous, on the plant body, Bailey, 

 90. 

 prodissoconch of Anoinia aculeata, 

 young, 20. 



of Avicida sterna, 20. 

 of Ostrea virginiana, 20. 

 of Pelecypoda, 19, 20. 

 of Spondijlus, 20. 

 smooth, of highly spinose spe- 

 cies of Spondylus, 18. 

 of Mollusca, 18. 

 of Ostrea, Anoinia, 

 Avicula, 18. 

 Product ella, 69, 231, 245, 270. 

 giganteus, 270. 

 spine growth in, 96. 

 Producti, spiny, 96. 

 Productidie, extinction of, 96. 

 Prodiictus, 69, 237, 245, 260, 270, 395. 

 absence of straight hinge-line in 



young, 268. 

 spine growth in, 96. 

 spiral impressions ou valves of, 276, 

 Proetid(^, 129, 139, 141. 

 defined, 148. 



fourth annulation in, 127. 

 lobes in glabella in, 149. 

 Proetus, 113, 129, 141, 143, 148, 176, 177, 

 179. 

 decor us, 175. 

 eyes in, 126, 148. 

 features of dorsal shield of, 182. 

 fixed-cheeks in, 148. 

 free cephalic segments in, 118. 

 glabella in, 135. 

 larvae of, 128. 

 lobation of glabella in, 148. 

 parviuscnlus, 175. 



original description of. Hall, 

 175. 

 projections, spiniform, on shells of Mol- 

 lusca, 9. 

 prominences, spinous, on test of Crusta- 

 cea, 9. 

 Proparia, 124, 129, 131, 132, 153. 

 defined, 152. 

 earliest forms of, 152. 

 history of, 31. 

 Prosopiscus, 153. 

 Protagranlus, 142. 

 Protaspis, 167, 169. 

 characters of, 169. 

 geological history of, 123. 

 homologies of, 170. 

 restoration of, 185. 

 stage in trilobites, 121, 122. 



