VI IT. 



,£"'] PROCEEDINGS OF THE NATIONAL MUSEUM. 249 



are keeled for a shorter distance than in the right valve, are generally 

 fainter, while the microscopic sculpture is composed only of fine concen- 

 tric incremental lines which have a silky appearance; the hinge line of 

 the left valve slightly overrides that of the other valve and is serrate by 

 fine transverse scales; the ears are subequal, the byssal notch shallow 

 and rounded, without a pectinium; there are a few elevated radiating 

 lines on these ears; internally the hinge line is nearly smooth, the car- 

 tilage pit small and narrow, two short, stout auricular lime radiate from 

 it; the interior of the shell is white; the interspaces between the ex- 

 ternal ribs are defined by fourteen or fifteen pairs of elevated lirse 

 strongest distally and ending close to the margin. Maximum altitude 

 of shell 60.0; maximum longitude 60.0; longitude of hinge line 25.0; 

 diameter of closed valves 11.0 mm . 



This fine species was not at first recognized from Professor Verrill's 

 rather brief diagnosis, which was not accompanied by a figure; and in 

 this way a new name was applied to the species in a preliminary notice 

 of it. More mature consideration, though without comparison of spec- 

 imens, leads me to the belief that Professor Verrill's name applies to 

 the shell before me. 



Although a ribbed species, the internal lirre are very much like 

 those of Amusium, and this shell adds one more to the links which con- 

 nect the various groups of the old genus Pecten together. A careful 

 comparison has been made with European species, and there can be no 

 doubt of the distinctness of this from any of them. 



Pecten exasperatus Sowerby. 



The collections made on the voyage contain a valve of Pecten cxas- 

 peratus Sowerby (P. fuscopurpureas Conrad) from Station 2762, in 59 

 fathoms, mud, off Rio Janeiro. This considerably extends the south- 

 ward range of this species beyond the localities previously known. 



Pecten effluens Dall. 

 Plate xi, Fig. 9. 

 Pecten effluens Dall, Bull. Mus. Comp. Zool., xn, p. 219, September, 1886. 



This hitherto unfigured and very delicate little species was originally 

 dredged off Havana by Sigsbee in 127 fathoms. Since then it has 

 been obtained in 300 fathoms off Cape San Antonio, Cuba, by Dr. Rush 

 and at U. S. Fish Commission Station 2646, in 85 fathoms, sand, off 

 Cape Florida. 



The valves may be pale or even bright lemon-yellow, orange or scar- 

 let, always somewhat translucent. The surface presents an excellent 

 example of the microscopic Camptonectes striation. The specimen fig- 

 ured is 26.0 mm in length. 



