DESCRIPTION OF PLATES. XVU 



FIG. PAGE 



160. Scrupularia swuposa, with bird's-head processes 



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



161. Snake-headed zoophyte Anyuinaria 73 



162. Flustra foliacea sea mat 72 



163. Plumatdla repens, a fresh-water polyzoon 74 



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



165. Transverse section of shell of Pinna, showing 



prismatic shell structure 74 



166. Longitudinal section of shell of Pinna 75 



167. Transverse section from oyster-shell 7 ft 



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. Teeth of whelk 73 



172. Teeth of limpet 75 



173. Teeth of periwinkle 73 



174. Teeth of Limneus 75 



175. Scale of sturgeon ganoid 7^ 



176. Prickle from back of skate placoid 7 



177. Borings by a minute parasite in a fossil fish-scale. . ^7 



178. Scale of sole ctenoid * 



179. Scale-, "whiting cycloid 77 



a. CuL-^eous particles, magnified. 



180. Scale of sprat cycloid 7V 



181. Section of egg-shell 90 



182. From soft egg. 



183. Section of egg-shell of emu 90 



PLATE VI I. to face page 80. 



184. Human hair , . . , 78 



a* Transverse section of human hair. 



