709 



postice divaricatim striatis costellatu; umbonibus elevatis; late- 

 ribus declivibus ; margiiie dorsali complanatim excavato ; lunula 

 impressa. 



A well- sculptured shell similar to the preceding, but having 

 the concentric ridges very numerous and (in the front part of 

 the shell) reflected ; at the back of the shell they are spread and 

 striated divergently. Ligamental area very smooth and deeply 

 excavated. Fig. 17 is from a specimen in Mr. Cuming's collec- 

 tion; f. 18 is from one in Mr. Hanley's collection, wliich I place 

 rather doubtfully with it. 



California. 



17. Venus Gnidia (pi. cliv. f. 35), Broderip et 8owerhy, 

 Zool. Journ. vol. iv. p. 364. 



" V. testa aequivalvi, subventricosa, liris concentricis muricatis 

 distantibus, striis radiantibus decussantibus, antice spinosioribus." 



The concentric ridges are very distant and produced into a 

 series of broad spines ; their under side is ribbed in correspond- 

 ence with the radiating ribs, which are alternately single and du- 

 plicate. The hinder side of the shell is rather pointed, with the 

 dorsal margin considerably sloping. 



Pacific Ocean. 



18. Venus Amathusia (pi. cliv. f. 26, 27), PMlippi, Ab- 

 bild. t. 11. f. 4. V. encausta, ? 



"V. testa cordato-triangulari, tumida, crassa, longitudinaliter 

 sulcata, transversim rugosa; rugis distantibus, sequalibus, inte- 

 gris ; area oblonga, depressa ; lunula late cordata." 



The shell here figured (f. 2G), from Mr. Hanley's collection, 

 perfectly agrees with the figure in Philippi above quoted ; it is 

 evidently an ill-developed and much-worn shell. Our second 

 figure (f. 27) however represents a perfect shell, from Mr. 

 Cuming's collection; these two are brought together by inter- 

 mediate specimens, and present a species so closely resembHng 

 F. Gnidia as to render the separation extremely doubtful. The 

 concentric scalloped ridges are much less prominent, and are 

 covered on the under side by a drown, shining enamel ; while 

 those of V. Gnidia are of the same texture as the other parts of 

 the shell. This may possibly indicate a difference in the habit 

 of the animal. 



Cahfornia. 



