292 REPORT ON ALBATROSS MOLLUSCA DALL. 



Iu the typo of Poromya the pallial sinus is obsolete; its retractor 

 muscles are either mainly incorporated in the septum, the muscular 

 contractions of which serve to move the siphons, or they are replaced 

 by the septal muscles. In the present species, however, there is a large 

 and strong pallial sinus with its usual muscles, and the septum is con- 

 sequently only very slightly furnished with muscular fibers, aud does 

 not serve to retract the siphons. The valve to the branchial siphon is 

 large, and the palps are enormous. The anterior edges of the anterior 

 palps are notched or papillose toward the median line, a condition not 

 observed in the other species. The foot is pointed aud slightly genicu- 

 late. There are seven anterior aud eight or nine posterior gill lamelhne; 

 the two areas are rather narrow, and their ends closely approach one 

 another near the middle of the foot on each side. In front of the 

 ridge which precedes the large branchial valve, and between it aud the 

 foot, are four or five quite prominent elevations of the surface, closely 

 resembling the branchial latnelhie, but with their length in the axial 

 direction of the animal. There are no fissures between these, but they 

 seem very like branchial lamellae iu process of development. Both the 

 longitudinal branchial areas on each side are fissured, aud their blood- 

 vessels reach them from behind. 



Suborder MYACEA. 



Family COBBULID^. 



Genus CORBULA Bruguiere. 



Corbula Dietziana C. B. Adams. 



This species was obtained at the Abrolhos Islauds,near Porto Allegre, 

 Brazil. It extends northward to Cape Hatteras, and was previously 

 known to extend southward only among the Antilles. 



Corbula Barrattiana C. B. Adams. 



Corbula disparilis Orbigny. 



Corbula cymella Dall. 



The above mentioned three species were collected at Statiou 2758, 

 90 miles southeast from Cape Sau Boque, iu 20 fathoms, shelly bottom, 

 oft" the Brazilian coast. 



Family SAXICAVID^: 



Genus SAXICAVA F. de Bellevue. 



Saxicava arctica Linne\ 



This well known shell, indistinguishable from Greenland specimens, 

 was collected at Stations 2708 and 2770, off Cape Delgado and Spiring 

 Bay, eastern Patagonia, in 43 and 58 fathoms, sand. 



