DESCRIPTION OF PLATES. 



no. PAGE 



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



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



161. Snake-headed zoophyte Anguinaria ..... ..... 78 



162. Flustra foliacea sea mat .................... 72 



168. Plvmatella repens, a fresh-water polyzoon ........ 74 



164. Egg of Cristatella Mucedo, 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 ............ 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. Teeth of whelk .............................. 73 



172. Teeth of limpet.. .. .......................... 75 



173. Teeth of periwinkle ...... . ........... . ....... 73 



174. Teeth of Limneus ........ . ................... 7@ 



175. Scale of sturgeon ganoid .................... 73 



176. Prickle from back of skate placoid ............ 75 



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



178. Scale of sole ctenoid ........................ 77 



179. Scale of whiting cycloid ...................... 77 



a. Calcareous 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 VII, to face page 80. 



184. Human hair ,.,.*. , , 7< 



a. Transverse section of human hair. 



