TERTIARY MOLLUSCA. 141 



Locality. Long Island, Antigua, station 6869, Vaughan. 

 Geologic horizon. Oligocene. 

 Type.U. S. Nat. Mus. No. 167107. 



Pecten nodosissimus, new species. 

 (Plate 7, Figure 3.) 



The following is a description of this species : 



Right valve nearly flat, equilateral, with 15 ribs equal in width to the inter- 

 spaces. Each rib has 3 lines of bead-like nodes, 1 median line and 2 lateral 

 lines. Submargins strongly convex, apparently smooth and sharply differ- 

 entiated from the ears. The ears are broken, but appear to have been rather 

 large; the left posterior ear had several faint radiating threads. 



Altitude, 25 mm. 



The sculpture of this shell is so peculiar that I have ventured to 

 describe it in spite of its fragmentary condition. 



Locality. Willoughby Bay, Antigua, station 6881, Vaughan. 

 Geologic horizon. Oligocene. 

 Type.U. S. Nat. Mus. No. 167131. 



Pecten perlineatus, new species. 

 (Plate 10, Figure 5.) 



The following is a description of this species : 



Left (?) valve flat, equilateral, with 16 round ribs with wider shallow, con- 

 cave interspaces; radial sculpture of fine, close-set, raised lines covering both 

 ribs and interspaces; submargins convex; ears much depressed below the plane 

 of the disk. 



Alt., 35 mm.; lat., about the same. 



Locality. Willoughby Bay, Antigua, station 6881, Vaughan. 

 Geologic horizon. Oligocene. 

 Type. U. S. Nat. Mus. No. 167130. 



Pecten nugenti Brown ? 



(Plate 10, Figure 6.) 

 Pecten nugenti Brown, Proc. Acad. Nat. Sci. Phila., p. 614, plate 19, figs. 2, 5, 6, 1913. 



The following is the original description of this species: 



"Shell inequivalve, oval in outline, with 17 distinct rounded radial ribs 

 (and probably 2 additional less distinct ones) separated by narrower inter- 

 spaces, the whole exterior surface covered by concentric growth lines which 

 are raised and produce a nearly microscopic sculpture extending equally over 

 ribs and interspaces. Internally smooth, except near the margin, where 

 raised ribs are seen, occupying the intervals between the raised external ribs. 

 On the flatter valve, externally the raised ribs are equal in width with the 

 intervals between them, and the concentric sculpture, while extending over 

 ribs and interspaces, is stronger in the intervals between the ribs. Ears 

 moderate, apparently not ribbed. The specimens vary considerably in size; 

 the one figured, a small specimen, measures: Length 41 mm. by height 36 mm. 

 Others were much larger, attaining a length of 55 mm. or more." 



