EXPLANATION OF PLATE XXIV. 



FIGUIIE 137. Littorina rudis, (p. 651 ;) natural size. 



138. Littorina palliata, (p. 652 ;) natural size. 



139. Lacuna vincta, (p. 652;) enlarged. 



140. Littorinella miuuta, (p. 653 ;) enlarged. 



141. Rissoa aculeus, (p. 654 ;) enlarged. 



142. Skenea plauorbis, (p. 655;) enlarged. 



143. Odostoinia producta, (p. 656;) enlarged. 



144. O. fusca, (p. 656;) enlarged. 



145. O. trifida, (p. 656 ;) enlarged. 



146. O. trifida, var., (p. 656 ;) enlarged. 



147. O. inipressa, (p. 656;) enlarged. 



148. O. semimida, (p. 657;) enlarged. 



149. Eulima oleacea, (p. 655;) natural size. 



150. Cerithiopsis terebralis, (p. 648 ;) enlarged. 



151. C. Emersouii, (p. 648;) enlarged. 



152. Triforis nigrocinctus, (p. 648 ;) enlarged. 



153. Cerithiopsis Greeuii, (p. 647;) enlarged. 



154. Bittiura nigruni, (p. 648;) enlarged. 



155. Turbouilla elegans, (p. 657;) much enlarged. 



156. Margarita obscura, (p. 661 ;) natural size. 



157. Vermetus radicula, (p. 649;) natural size. 



158. Caecum pulchellum, (p. 649 ;) natural size and enlarged. 



159. Acnuea testudinalis, (p. 661 :) natural size. 



159a. The same ; lower side, 



1596. The same, variety alveus ; natural size. 



(Figure 155 was drawn from nature, by A. E. Verrill ; the others are from Binney s Gould, mostly 

 drawn by E. S. Morse.) 



