DESCRIPTION OF PLATES. XVU 



FIG. PAGE 



160. Scrnpularia scruposa, with bird's-head processes 



{avicularia) and sweeping bristles (vibracula). . 73 



161. Snake-headed zoophyte — Anguinaria 73 



162. Flustra foliacea — sea mat 72 



163. PkimatcUa repens, a fresh- water polyzoon 74 



164. Egg of Cristatella Mucedo, a fresh-water polyzoon 74 



165. Transverse section of shell of Pinna, showinar 



prismatic shell structure 74 



166. Longitudinal section of shell of Pinna, 75 



167. Transverse section from oyster-shell 75 



168. Section of shell of Anomia, with tubular borings. . 75 



169. Section of mother of pearl 75 



170. Prawn-shell viewed as a transparent object 75 



171. Teethofwhelk 76 



172. Teeth oflimpet 75 



173. Teeth of periwinkle 75 



174. Teeth of Limneus 73 



175. Scale of sturgeon — ganoid 75 



176. Prickle from back of skate — -placoid yg 



177. Borings by a minute parasite in a fossil fish-scale. . 77 



178. Scale of sole — ctenoid «y 



179. Scale of whiting — cycloid ^7 



a. Calcareous particles, magnified. 



180. Scale of sprat — cycloid 7V 



181. Section of egg-shell 90 



182. From soft Qgg. 



183. Section of egg-shell of emu 90 



PLATE VII. to face page 80. 



184. Human hair 73 



a. Transverse section of human hair. 



