344 



PROCEEDINGS OF TEE NATIONAL MUSEUM. 



VOL. 57. 



Notwithstanding the fact that MagaseUa aleutica is neatly shaped 

 and prettily colored while Terehratalia frontalis is dull gray, coarse 

 and usually misshapen, I am pretty well satisfied that the former 

 should be referred to the immature stage of the latter. 



T. frontalis has an enormous pedicel opening with inconspicuous 

 widely separated deltidia, no septal ridge in the pedicel valve, short 

 props to the dental processes and the faintest possible indication of a 

 pro tractive fold on the anterior edge of the valve; the brachial valve 

 has a small cardinal process, there is a narrow platform with a con- 

 cavely arcuate anterior edge between the crural ridges; instead of a 

 septum a sharp groove starts from under the platform in the cavity 

 of the beak and extends beyond the middle of the valve where a low 

 short triangular septum, much farther forward than usual, rises out 

 of the groove to support the loop. Davidson's figures show the crural 

 plates entirely separated but this is not the case with my specimens. 

 The muscular impressions are more widely separated than in the 

 other species of the group. Upon these characters Allan Thomson 

 has separated this species generically from Terehratalia. 



TEREBRATALIA GOULDH Dall. 



Terebratella gouldii Dall, Proc. Acad. Nat. Sci. Phila., for 1891, p. 167, pi. 4, 



figs. 4, 5. 

 7 MagaseUa gouldii Dall, Proc. Zool. Soc, 1871, p. 307, pi. 31, figs. 11 a-c— 



Davidson, Proc. Zool. Soc, 1887, p. 96, pi. 17, figs. 20-22 (immature stage). 



Hakodate, W. Stimpson. 



Type locality. — East coast of Japan between Yedo and Oshima. 

 F. Stearns. 



I am not so sure that the Terehratalia is the adult of the above- 

 mentioned MagaseUa as I was at first, but in any case the specific 

 name holds for the former. This species is thin with a weak hinge, 

 a well marked "collar" within the foramen and no septal ridge; the 

 teeth are normally propped. In the brachial valve there is a feebly 

 developed cardinal process, the crural ridges are not united mesially, 

 a very short low septum, almost entirely behind the muscular impres- 

 sions which are very adjacent, receives the attachment of the loop 

 some 5 millimeters in front of the beak in a specimen 28 millimeters 

 high. In front of the septum are two short diverging raised lines about 



