324 PROCEEDINGS OF THE NATIONAL MVSEUM. vol.xxiii. 



blunt point; surface sculptured only with faint incremental lines; 

 hin^e normal, strong for the size of the shell; pallial sinus discrepant, 

 in the right valve small, gibbous, short, about two-thirds confluent 

 below; in the left valve large, reaching nearly to the anterior adductor 

 scar, and three-fourths confluent below. Lon. 14, alt. i>, diam. 4 mm. 



Ty2}e«.~^o. 108652, LT.S.N.M., dredged at Lituya Bay, Alaska, 

 in 8 fathoms, sand, by W. H. Dall, at station 1126. The species was 

 also obtained in 12 fathoms, mud, in Sitka Harbor, at station 1109. 



This little shell looks externall}' like an Aiujidiis^ but internally has 

 the characters of 2[acoina. It is not closel}" related to an}- of the other 

 Macomas of the coast. 



MACOMA (INDENTATA Carpenter, var.?) TENUIROSTRIS Dall. 



Macoma indentata Carpenter, Proc. Cala. Acad. Nat. 8ci., Ill, 1866, p. 119 {ex jxtrte). 



The species cited was founded upon two lots of specimens, both from 

 San Pedro, California, one young (Palmer) and fresh, the other (Cooper) 

 dead, more or less worn valves. Dr. Carpenter remarks that it ""dif- 

 fers from 2L Kriihonella Lamarck in its -sYV^'ri'-like post-ligamental wing. 

 This being rubbed ofl' in the large dead valves, the shell [in them] has 

 the aspect of a very distinct species." An examination of the mate- 

 rial in the collection of the U. S. National Museum shows that the 

 difference above alluded to b}" Dr. Carpenter does not rest alone on the 

 absence of the post-ligamental wing. The typical indentata is a 

 shortei", smaller, flatter, and much less rostrate shell, ])esides being 

 more inequiA^alve. For the rostrate form, pending the acquisition of 

 more and fresh material, I would propose the varietal name of tenui- 

 7'ostrls. It measures: lon. 55, alt. 33, and diam. 16 mm. The nearest 

 specimen of the typical form measures respectivel}- -ll, 31, and 12 mm. 

 The beaks are 25 mm. behind the anterior end and in tenuirostris 33 

 mm. behind it. The left valve is notalily flatter than the other in the 

 type, while in the only pair we have of the variet}' the valves, though 

 flexuous, hardly differ in degree of convexity". 



MACOMA (PSAMMACOMA) PANAMENSIS new species? 



(Plate IV, fig. 3.) 



Shel! elongated, slender, thin, inequilateral, moderately convex, 

 whitish; surface finely concentrically striated with (especially toward 

 the basal margin) numerous obscure radial striulations; beaks rather 

 low, anterior end longer, evenly rounded, posterior end produced, 

 attenuated, andsubrostrate; periostracum delicate, j^ellowish, dehiscent; 

 hinge normal; pallial sinus long, but rather distant (in the left valve) 

 from the adductor scar, about half confluent below, the interior of the 



I 



