136 GEOLOGY AND PALEONTOLOGY OF THE WEST INDIES. 



anterior ridge and two marked posterior grooves with a ridge between them. 

 Adductor scar large, with a rather ragged margin. Right valve with eleven 

 stronger ribs, each carrying five or six riblets, with two or three similar riblets 

 in the interspaces ; the proximal halves of the ribs are slightly undulated but 

 not scaly; ears subequal, rudely imbricate on the dorsal margin and on the 

 four or five radial threads of the anterior ear; ctenolium with about 16 spines, 

 byssal notch narrow, angular; hinge-line grooved reciprocally to that of the 

 left valve. Height 132; length of shell 152; of hinge-line 82; max. diameter 

 omitting spines 46 mm. 



"This fine and remarkable species is somewhat intermediate between 

 Lyropecten and Nodipecten, and when young must have the aspect of a Chlamys 

 much like C. imbricatus." 



The figured specimen, a right valve from the gorge of Yumuri 

 River, Cuba, is smaller than the type and has higher ribs. It measures 

 68 mm. in altitude and 72 mm. in latitude. A fragment of a left valve 

 measuring 190 mm. in altitude has been obtained near the mouth of 

 Macambo River, Cuba. 



Localities. Moin Hill, near Port Limon, Costa Rica, niveau a 

 Pittier (type); gorge of Yumuri River below Iglesia Mont Serrato, 

 Matanzas, Cuba, station 3468, Vaughan (figured specimen) ; Santiago, 

 Cuba, station 5255, Black; near mouth of Macambo River, Cuba, 

 station 7533, Meinzer. 



Geologic horizon. Oligocene. 



Type.U. S. Nat. Mus. No. 214368. 



Figured specimen. U. S. Nat. Mus. No. 167123. 



Pecten (Nodipecten) articulosus, new species. 

 (Plate 7, Figures 7, 8.) 



The following is a description of this species: 



Shell moderately large, nearly equivalve, slightly oblique, convex; sculpture 

 of 8 to 11 large round ribs with equal concave interspaces, smooth except for 

 close, faint, radial striations which appear distally on both ribs and inter- 

 spaces of large specimens; ribs on right valve obscurely nodular, ribs on left 

 valve prominently nodular, the undulations affecting the whole of the disk 

 as in P. condylomatus; submargins rather wide, compressed in the umbonal 

 region but expanding distally, smooth, except for close faint radial strias on 

 the distal portion; ears small, subequal, the surface faintly radially threaded. 



Alt. of right valve (type) 55 mm., lat. 61 mm., diam. 19 mm.; alt. of left 

 valve 55 mm., lat. 58 mm. (edge broken), diam. 19 mm. 



This species resembles Pecten condylomatus Dall in shape and size, 

 but is more nearly equivalve, has larger and fewer ribs, and lacks the 

 secondary sculpture. It is represented in the collection by 3 right 

 valves and 4 left valves. 



Locality. Disintegrated limestone in a quarry near asylum near 

 Guajay, 15 miles southwest of Havana, Cuba, Barnum Brown, col- 

 lector. 



Geologic horizon. Oligocene. 



Type. American Museum of Natural History. 



