402 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



A single valve of this rather remarkable shell was brought to the 

 United States National Museum from Topolobampo, Mexico, by Pro- 

 fessor Daniels. Cat. No. 126352, U.S.N.M. 



CALLOCARDIA CATHARIA, new species. 

 Plate XIY, iig. 3. 



Shell large, white, somewhat earthy, with a pale olive periostracum; 

 beaks high, prominent, strongly anteriorly directed over a large cord- 

 ate lunule delimited by an impressed line; extremities slightly pro- 

 duced, base arcuate; anterior slope short and straight, posterior 

 arched, a shallow sidcus cutting off a narrow raised area on each side 

 of the ligament; surface more or less shining, finely, closely, sharply 

 concentrically sulcate; the middle of the shell in the earlv stages 

 smooth or with the sulcations feeble, but in the adult they are uni- 

 formly continuous: interior white with a faint salmon flush in the 

 cavit}' of the beaks; pallial sinus very near the margin, exceptionally 

 wide and shallow, rounded in front: the muscular impressions quite 

 small; hinge well developed, normal. Length, 52; height, 43; diame- 

 ter, 30 mm. 



Bay of Panama, in 30 fathoujs, nuKk at station 2799, United States 

 Fish Commission steamer Alhatro.ss. Cat. No. 9636S, U.S.N.M. 



The species appears to be abundant and always pure white exter- 

 nally. The pallial sinus seems to vary in form; in the younger shells 

 it is relatively narrower and more angular, in the adults shorter and 

 moi-e rounded. Thos(> differences are rather surprising, as the form of 

 the pallial sinus in most bivalves is fairly constant. 



PITARIA TOMEANA, new species. 

 Plate XV, iig. 2. 



Shell small, yellowish white, rather earthy in texture, smooth except 

 for very fine concentric wrinkles: beaks small, pointed; lunule small, 

 defined by a feebly impressed line; periostracum thin, papyracous; 

 interior white, margins entire, the area within the pallial line earthy, 

 the pallial sinus linguiform, short; hinge normal, solid, the anterior 

 lateral subconical. Length, 23.5; height, 20; diameter, 12 mm. 



Brought up with mud on the anchor at Tome, Chile, by the United 

 States Fish Commission steamer A/hatnm.. Cat. No. 109220, U. S. N.M. 



This is an inconspicuous little species, which may in some instances 

 develop color markings, though the specimens obtained do not. 



PITARIA (LAMELLICONCHA) CALLICOMATA, new species. 

 Plate XVI, fig. 8. 

 Shell white, rather earthy, moderately convex, elongate ovate; cov- 

 ered with prominent sharp, thin, concentric lamella?, everv third or 

 fourth of which is higher than the others; near the anterior end the 



