840 rilOCEEDINdS OF THE NATIONAL MUSEUM. VOL.XX. 



closely crowded, often even in contact in the radial rows, and in 

 form either rounded or elliptical with the longest diameter in the 

 direction of the concentric lines, with the summit evenly rounded, 

 showing no tendency to the subconical or mucronate form. When 

 perfect they resemble small blisters with the surface roughened or 

 minutely granulose under the microscope; when broken or worn off, as 

 frequently happens, the basal part remains in the form of a semicircular 

 or semieliiptical, imbricated, arched scale, usually considerably ele- 

 vated above the surface and connected by very delicate concentric 

 raised lines. The surface of the anterior auricle of the left valve is 

 roughened by close, elevated, concentric lines, and from four to six 

 well-marked radiating ridges or ribs, upon which the concentric lines 

 form regular elevated arched projections, often so crowded as to be 

 imbricated; in some young examples, like the one figured, the concen- 

 tric lines on the auricle are less crowded and only two or three of the 

 radial ribs are developed ; in such examples the vesicles on the body 

 of the shell are relatively fewer, larger, more rounded, and much less 

 crowded in the radial series. Jn some specimens the posterior margin, 

 below the auricle, is nearly smooth or marked only by the fine lines of 

 growth, while in others, especially larger specimens, this region is cov- 

 ered by rather sharp granules, some of which, toward the ventral 

 margin, change to pointed scales arranged in crowded radial rows. 

 The raised concentric lines on the right valve are generally more or 

 less appressed and sometimes imbricated ; toward the ventral margin 

 some of them show very fine microscopic creuulatious, which are much 

 less distinct than on <?. imbrifer, as figured by Sars. 



This species is distinct from that figured by Mr. Dall 1 under the 

 name of C. imbrifer. His specimen apparently belongs to the follow- 

 ing species. 



Several live and dead specimens, at eleven stations between N. lat. 

 44 34', W. long. 56 41' 45", and K lat. 39 48' 30", W. long. 70 54', 

 in 99 to 547 fathoms, 1872-1885. 



CYCLOPECTEN SUBIMBRIFER Verrill and Bush. 

 (Plate LXXXV, figs. S, 9.) 



Pectcn hoskynsi VERRILL, Trans. Conn. Acad., V, p. 581, pi. XLIV, fig. 11, 1882. Not 



Forbes. 

 Peel en (Pseudamusium) imbrifer DALL, Bull. Mns. Comp. Zool., XII, p. 220 (in 



part), pi. iv, figs. 4, U, 1886; Bull. U. S. Nat. Mus., No. 37, p. 34 (in part), pi. 



iv, figs. 4, 4fc, 1889. 

 Cyclopeeten subimbrifer YERRILL aud BUSH, in VERRILL, Trans. Conn. Acad., X, 



pp. 84, 92, 1897. 



Shell small, inequivalved, white or grayish white, translucent, length 

 and height nearly equal. Dorsal margin straight. Anterior auricle in 

 the left valve rather large and broad, the outer end obtusely rounded, 



1 Blake Mollusca, pi. iv, figs. 4a, 4&. 



