Xll THE MICROSCOPE. 



FIG. PAGE. 



161. Transverse section of shell of Pinna, showing 



prismatic shell structure 55 



162. Longitudinal section of shell of Pinna 56 



163. Transverse section from oyster-shell . 58 



164. Section of shell of Anomia, showing tubular shell 



structure 56 



1 65. Section of mother of pearl 56 



166. Section of prawn-shell 56 



167. Teeth of whelk 57 



168. Teeth of limpet 57 



169. Teeth of periwinkle 57 



170. Teeth of Limneus 57 



171. Scale of sturgeon ganoid 57-69 



172. Prickle from back of skate placoid 57 



173. Borings by a minute parasite in a fossil fish-scale . 58 



174. Scale of sole ctenoid 58 



175. Scale of whiting cycloid 58 



a. Calcareous particles, magnified. 



176. Scale of sprat cycloid 58 



177. Section of egg-shell 70 



a. From soft egg. 



178. Egg-shell of enm 70 



PLATE VII. 



179. Human hair 59 



a. Transverse section of human hair. 



1 80, a. Small mouse-hair 60 



b. Larger mouse-hair. 



c. Plain mouse-hair. 



d. Minute hair from ear of mouse. 



