ACANTHOCHITES. 19 



Length 30, breadth 20 mill. (Gl'd.} 



Kikaia and Hakodadi Bay, Japan (Stimpson.) 



C. (Acanthooficetes') achates GOULD, Proc. Bost. Soc. Nat. Hist, vii, 

 p. 165 ; Otia Conch., p. 118. 



One of the orginal specimens of this species is before me, but it is 

 so eroded that the characters are quite obscured. 

 A. DEFILIPPII Tapparone Canefri. PL 2, figs. 45-48. 



Shell ovate, the valves small ; girdle closely hairy, very wide. 

 Valves heart-shaped, narrowed in front, dilated, and somewhat 

 beaked in the middle behind; last valve small, subrotund. 

 Umbones obscurely transversely striated, areas minutely and closely 

 granulated. Girdle much dilated, thick, densely covered with short 

 haiis, and having two series of setigerous pores. Color of the valves 

 black-brown, sometimes variegated with white ; girdle olive-brown, 

 the pore tufts black. (7.-C.) 



Yokohama, Japan. 



Amycula de-filippii T.-C. Zool. del Viaggio intorno al globo della 

 R. Fregata ' Magenta,' Malacologia, p. 78, t. 1, f. 15, 15a-2c. (1874). 

 Stectoplax porrecta CPR., MS. and in Dall, Proc. U. S. Nat. Mus. 

 1881, p. 288 (no description.) 



Canefri's figure of this species shows but seven valves, probably a 

 mistake of the artist. 



The species described by Carpenter seems to be identical. Car- 

 penter's name was applied some years before the appearance of the 

 Zoology of the 'Magenta/ but unfortunately was never published. 

 The Carpenterian species is evidently what Tapparone-Cauefri 

 alludes to as a species of " Stretochiton " in the collection " del sig. 

 E. Adams." Carpenter's description is as follows : 



A. porrectus Carpenter. (PL 2, figs. 36-44). Valves two-thirds 

 immersed, brown-olive ; exposed part of the posterior valve rounded, 

 the mucro a little behind the middle; anterior valve semicircular; 

 median valves trilobed, projecting far forward at the ridge. Dorsal 

 area smooth, in the young shell longitudinally striate and granulose. 

 Side areas conspicuously granose. 



Interior : posterior valve mopaloid, slightly sinuated behind, hav- 

 ing one slit at each side. Anterior valve having 5 slits; median 

 valve 1 slit (or sometimes abnormally 2 on one side) ; posterior 

 teeth long, the rest very long ; eaves minute. Jugal sinus very deep, 

 wide, smooth, sutural laminae separated. 



