346 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 57. 



cular scars but not extending into the beak, nor attaining the pro- 

 portions of a septum. The interior of the valve is marked by numer- 

 ous radiating, bifurcating shallow furrows. The brachial valve is 

 medially provided with a broad depression and produced to occupy 

 the sulcus in the opposite valve; there is a strong bifurcate cardinal 

 process; the sockets are not cross-striated; there is a thick mass of 

 callus bridging the gap between the stems of the crura; the loop ex- 

 tends nearly to the anterior edge of the valve. In this valve also 

 a thick low ridge, grooved medially, extends from the callous mass 

 between the crura forward between the thickened muscular scars. 

 Out of the groove rises a very low thin short septum, the junction 

 with the cross band of the loop is little elevated and slightly behind 

 the middle of the valve. The interior of this valve is furrowed like 

 the other valve. The shell is solid and tends to form callosities with 

 age. It reaches a width of 53, a height of 52, and a diameter of 

 32 mm. 



TEREBRATALIA XANTHICA, new species. 



Shell bright yellowish-brown, transverse, inflated, smooth except 

 for feeble incremental lines, the brachial valve feebly mesially exca- 

 vated, but showing hardly any undulation at the anterior edge. The 

 deltidia are coalescent in the young, widely separated in the adult, 

 the adult foramen large, showing no "collar;" the props to the dental 

 plates obsolete, no septum or mesial ridge between the muscular 

 scars, and two short vermicular genital sinuses on each side. 



Brachial valve with no cardinal process, the crural stems separated 

 to the apex, a short wide loop with a low short septum amd one genital 

 sinus on each side. A young specimen which appears to be of the 

 same species, however, has the crural stems united by a concave 

 platform continuous with the posterior end of the septum which 

 divides the space beneath the platform into two cavities. Height of 

 shell, 25; width, 33; diameter, 19 mm. 



Type locality. — Japan Sea in 86 fathoms, sand, at United States 

 Bureau of Fisheries station 4996. 



This species presented something of a puzzle, and at first I was dis- 

 posed to regard it as an extreme variation of T. coreanica, but on 

 careful study the differences appeared so great that I concluded to 

 place it separately. The transverse form, the absence of the broad 



