G38 Mr. H. B. Preston on neic Felecjjpods 



rounded ; anterior side obtusely rounded ; posterior side 

 sloping above, rounded below, subtruncate ; rigiit valve 

 bearing two teeth, of wliich tlie anterior is very broad and 

 squarish and the posterior broad at the base somewhat 

 narrowing but obtuse at the apex ; left valve bearing a coarse, 

 rounded, nodulous, anterior tooth and a narrow, slightly 

 curved, posterior tooth ; hinge-plates moderately short and 

 narrow ; interior of shell white. 



Long. 3"5, lat. 5" 75 mm. 



Ilah. Port Stanley, Falkland Islands ; from the stomachs 

 offish {A. G. Bennett). 



Cyamhim exasperatum , sp. n. (Fig. 5.) 



Shell small, ovate, white, somewhat iridescent, sculptured, 

 especially towards the ventral margin, with concentric 

 growth-ridges; umbones moderately large, not prominent; 

 dorsal margin rather convexly sloping posteriorly, slightly 

 concavely sloping anteriorly ; ventral margin very slightly 

 curved ; anterior side rounded ; posterior side somewhat 

 truncate ; anterior cardinal in right valve broad, oblique, 

 posterior cardinal small, very oblique ; anterior cardinal in 

 left valve small, very oblique, somewhat curved above, poste- 

 rior cardinal short, broad ; hinge-plates considerably pro- 

 jecting, especially in left valve ; interior of shell white. 



Long. 3'25, lat. 4*5 mm. 



JJah. Port Stanley, Falkland Islands ; taken from the 

 stomachs of fish [A. G. Bennett). 



Cyamium piscium, sp. n. (Fig. 6.) 



Shell subrectangular, rather thin, white, iridescent, showing 

 traces of having been covered with a thin, pale yellowish- 

 brown periostracum, sculptured with fine concentric stria^, 

 especially towards the ventral margin ; umbones large, some- 

 what prominent ; dorsal margin anteriorly sloping, angularly 

 excavated, posteriorly gently sloping ; ventral margin 

 slightly contracted in tlie median region; anterior side 

 rounded ; posterior side obtusely rounded, slightly produced ; 

 right valve bearing a large, nodulous, anterior cardinal aud 

 a small, oblique, posterior cardinal tooth; left valve bearijig 

 a rather fine, oblique, anteiior cardinal and a stronger and 

 less oblique jjosterior cardinal tooth ; hinge-})late mode- 

 rately projecting except in the riyht valve in front of the 



