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. 

 proUematicum, casts of, 426. 

 initial pores in, 426. 

 Pleurostomella alternans, single spine in, 



44. 

 plum, loss of spines of, by cultivation, 

 74. 

 spiniform branches of neglected, 75. 

 Plittonides, 142. 

 Podocyrtis Schomhurgki, terminal spine 



in, 44. 

 Polymorpliina Orhignii, compound spines 

 in, 68. 

 soToria, var. cuspidata, single spine 

 in, 44. 

 Polyzoa, 252. 

 Poramhonites, 245. 

 porcupine, extreme spinosity in, 70. 

 -men, 92. 



modified hairs of, 9. 

 protection of, by spines, 54. 

 Porifera, mural pores in, 76. 

 Poulton, E. B., mimetic features in early 



thorn moth, 62. 

 praemagadiform stage, 292. 

 pressure, results of, on an organism, 



Paget, 28. 

 Prestwichia, 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. 

 Proboscidella, 245. 



difference in valves in, 237. 

 Proceratopyge, 142, 145. 

 Procervulus, antlers in both sexes of, 57. 

 processes on Echinodermata, 9. 



spinous, on the plant body, Bailey, 

 90. 

 prodissoconch of Anomia aculeata, 

 young, 20, 



of Avicula sterna, 20. 

 of Ostrea virginiana, 20. 

 of Pelecypoda, 19, 20. 

 of Spondylus, 20. 

 smooth, of highly spinose spe- 

 cies of Spondylus, 18. 

 of MoUusca, 18. 

 of Ostrea, Anomia, 

 Avicula, 18. 

 Productella, 69, 231, 245, 270. 

 giganteus, 270. 

 spine growth in, 96. 

 Producti, spiny, 96. 

 Productidse, extinction of, 96. 

 Productus, 69, 237, 245, 260, 270, 395, 

 absence of straight hinge-line in 



young, 268. 

 spine growth in, 96. 

 spiral impressions on valves of, 276. 

 Proetidm, 129, 139, 141. 

 defined, 148. 



fourth annulation in, 127. 

 lobes in glabella in, 149. 

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

 179. 

 decorus, 175. 

 eyes in, 126, 148. 

 features of dorsal shield of, 182. 

 fixed-cheeks in, 148. 

 free cephalic segments in, 118. 

 glabella in, 135. 

 larvas of, 128. 

 lobation of glabella in, 148. 

 parviuscidus, 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. 

 Protagraulus, 142. 

 Protaspis, 167, 169. 

 characters of, 169. 

 geological history of, 123. 

 homologies of, 170. 

 restoration of, 185. 

 stage in trilobites, 121, 122. 



