602 PROCEEDINGS OF THE ACADEMY OF [NoV., 



specimen referred by Gabb to P. paranensis d'Orb. It was found at 

 Willoughby Bay, several specimens being taken. Gabb's specimen 

 came from the Reventazon River, Costa Rica, and not, as noted by 

 Dall, from Santo Domingo. 



Pecten (Chlamys) anguillensis Guppy. Plate XVIII, figs. 4, 6, 7, 8. 



Pecten anguillensis Guppy. — Proc. Sci. Asso. Trinidad, 1867, p. 175, figured 

 in Geol. Mag. Decade, II, Vol. I, 1874, pi. XVIII, fig. 24. 



This species was the commonest Pecten in the Antigua limestone, 



and is recorded as having been brought from Antigua by Spencer 



(see Dall, "Tertiary Fauna of Florida," p. 715). It was collected by 



me at Wetherill's, Hodge's Bay, and Willoughby Bay. It was 



particularly plentiful at Wetherill's Bay, but few specimens could 



be detached entire from the rock surfaces. The figure given by 



Guppy does not show the secondary radial striation, and is thus 



misleading, but the species may readily be recognized by its 10-11 



ribs, much fewer than in the other fossil Pectens of Antigua. Its 



living representatives, probably descendants in one case, are P. 



antillarum Recluz of Guadaloupe and other islands of the West 



Indies, and P. luculentus Reeve of North Australia. 



Pecten (.ffiquipecten) thetidis Sowb. 



Peclen thetidis Sowb.— Quart. Jour. Geol. Soc, VI, 1849, p. 52. 



Pecten thetidis Sowb. — Gabb, Trans. Amer. Phil. Soc, new series, XV, p. 256. 



This species was collected at Hodge's Bay, and agrees well with 



specimens so named by Gabb in his Santo Domingo collection in 



The Academy of Natural Sciences of Philadelphia. It was fairly 



common; did not become silicified so commonly as the last species, 



and commonly acquired a black color on exposure to the weather. 



The species is small, evenly ribbed, and seems to belong to the first 



of the two varieties mentioned by Gabb. 



Pecten (Plagioctenium) gabbi Dall. 



Pecten (Plagioctenium) gabbi Dall, Tertiary Fauna of Florida," p. 717, pi. 

 29, fig. 3. Not Pecten paranensis d'Orb., as cited by Gabb. — Jour. Acad. 

 Nat. Sci. Phila., 2d series, VIII, p. 347. 



This species is represented by one entire valve and several more 

 or less well-preserved fragments of valves from Willoughby Bay, 

 and, while it does not agree exactly with Dall's figure, it does agree 

 with his description of P. gabbi Dall. The figure is from a specimen 

 collected by Spencer in Antigua. The specimen referred to Pecten 

 paranensis d'Orb. by Gabb was from Reventazon River, Costa Rica, 

 not from Santo Domingo, as stated by Dall. As already noted, this 

 Costa Rica specimen is the P. oxygonum optimum B. and P., and does 



" Trans. Wagner Free Inst. Sci., Ill, p. 715. 



