90 MAZATLAN BIVAHVES 



a Gastrochffina truncata in its burrow, and a Petricola robusta 

 wkicli, after penetrating to the Prock, bas flattened itself 

 rather than bore into tbe harder substance. 



122. Chama spinosa, Brod. 

 Proc. Zool. Soe. 1834, p. 150.— -Ri'e. Conch. Icon, in loc. 



Three small Talves and one pair appear to belong to this 

 species. The valves differ from the yo;mg of C. frond, fornicata, 

 in having the entire surface crowded with semi-tubular spmes ; 

 and in the character of the margin, which is smooth and 

 rounded within, outside with crowded scales one on another, 

 like the base of Hipponyx tesseUata. The tj^es and the pair 

 do not display this structure, which appears very characteristic. 

 Hinge teeth comparatively smaU ; muscular scars not very 

 large ; colour white, with slight rosy tint at the umbos which 

 are scarcely spiral. Long. I'l, lat. I'l, alt. "08. 

 Sab.— Lord Hood's Island, Cuming.—? Mazatlan ; extremely 



rare ; L'pool Col. 



Tablet 444 contains a valve. The pair will be seen, attached 

 to Ostrea, with Discina, on tablet 20. 



123. Chama Pexogyea, Conr. 



One broken pair attached to a pebble, and a valve on Spondy- 

 lus calcifer in the Liverpool ]\Iuseum, differ from the rest ot 

 the Mazatlan Chama? in the following particulars, bheil sinis- 

 tral : veutrally produced ; surface roughened and aminated, 

 not spinous; margin smooth, rounded off, slightly crenate 

 outside ; teeth long, small, colour reddish brown, without 

 purple. They may belong to Ch. Panamensis, or even to Ch. 

 corrugata, but seem best to accord with this species. Long. 1 5, 

 lat. 1-17, alt. 1-15. 

 iZa6.-Sta. Barbara, San Diego, &c. iVw^teZZ.-Mazatlan ; ex- 



tremelj^ rare ; L'pool Col. 



Tablet 415 contains the specimen on pebble. 



Family CiVEDIAD^. 

 Genus CARDIUM, Linn. 



Only two species of this abundant genus were sent in any 

 quantity ; the shell washings however proved that many more 

 must exist in the neighbourhood ; 5 species bemg found sut- 



