10 



THE NAUTILUS. 



lines rather coarse and irregular, the entire surface covered with 

 low, coarse, rather distant radial striae extending to the edges. 

 Length 3.5, width 2.5, alt. 1 mm. 



Types, (No. 43454 Coll. Walker), from Butting Ram Shoals, 

 Coosa Co., Ala., collected by H. H. Smith. Cotypes in the 

 collections of T. H. Aldrich, George H. Clapp and John B. 

 Henderson. 



All of the specimens were found on living Plev.roceridse. 



This beautiful little species, which groups with rhodacmt in 

 its depressed shape and spine-like apex as well as in its radular 

 characteristics, differs from it in its small size, more regularly 

 oval shape and the greater development of radial striae over the 

 surface. 



It is named in remembrance of the late Rev. Prof. H. M. 

 Gwatkin of Cambridge, England, to whom I am indebted for 

 practically all of the radula preparations used in this paper and 

 who was the first to observe and point out the remarkable char- 

 acter of the radula in the different species of the genus. 



I am indebted to Dr. Pilsbry for the slide representing the 

 radula of Lanx patelloides. All of the other radula? figured 

 were prepared by Prof. Gwatkin, and all of the figures were 

 drawn by Mrs. Lydia M. H. Green formerly connected with the 

 U. S. National Museum. 



a :;lw spzciz3 of astaete feom alaska. 



BY WILLIAM HE A LEY DALL. 



In 1865 Dr. Philip Carpenter described from a single speci- 

 men a species of Astarte from Puget Sound, to which he gave 

 the specific name of compacta. This type remains in the collec- 

 tion of the National Museum as number 4509. 



This species has remained extremely rare, only three or four 

 others, some eroded and doubtful, have come to hand during 

 the half-century which has passed. This is probably due to 

 the fact that the right locality had not been dredged, for the 



