EXPLANATION OF PLATE XXVIL 



FiGur.E 186. — Teredo uavalis, (p. G69;) shell and pallets. 



187.— Teredo Thomsoni, (p. 670 ;) shell and pallets. 



188. — Teredo niegotara, (p. 670 ;) shell and pallets. 



189. — Xj'lotrya fimhriata, (p. 670;) shell and pallets. 



190.— Gastranella tnmida, (p. 678;) shell, enlarged sis diameters. 



191. — Corbula contracta, (p. 672 ;) natural size. 



192. — Saxicava arctica, (p. 671 ;) natural size. 



183. — Clidiophora trilineata, (p. 673;) natural size, -with animal. 



194. — Lyonsia hyalina, (p. 672;) natural size. 



195. — Thracia truncata, (p. 674 ;) natural size. 



196. — Thracia myopsis, (p. 673;) natural size. 



197. — Periploma iiapj^racea, (p. 673 ;) natural size. 



198. — Cochlodesma leanum, (p. 673 ;) natural size. 



189.— Petricola pholadiformis, (p. 680 ;) natural size. 



200. — Pholas truncata, (p. 670 ;) natural size. 



(Figure 190 was diawu by A. E. Tenill; all the rest are frpm Biuney's Goulil, mostly drawn by E. 

 S. Morse.) 



