40 ■ PROCEEDINGS OF THE ACADEMY OF [Feb.^ 



Height 29.2, length 28, semidiameter 9 mm. 



The ribs weaken rapidly towards the base, where they almost 

 disappear, reminding one of G. suhovata (Say). G. jamaicensis Dali 

 differs by its greater length, much less arched hinge line and fine 

 striation. 



Ostrea vaughani insularis n. subsp. PI. 6, figs. 1, la. 



The common large oyster of Santo Domingo resembles 0. vaughani, 

 as described and figm-ed by Dall, except in the following featm-es: 

 The beak is usually straight; the upper valve is very much smoother 

 than the lower, marked with growth-lines only, and it is usually 

 almost flat. The lower valve is thick, coarsely lamellar, not fluted, 

 and has a rather deep beak cavity. The valves have a sparse 

 denticulation inside near the hinge. Length of lower valve 106, 

 width 58 mm. It may perhaps be well to signalize these differences 

 by a subspecific name. 



Santo Domingo, W. M. Gabb. No. 2635, A. N. S. P. 



Ostrea cahobasensis n. sp. PI. 6, fig. 8. 



This oyster is similar to the preceding except that in a large 

 series of specimens none were found to have the inner margins of the 

 valves denticulate near the hinge. The upper valve is nearly flat 

 and is perhaps somewhat rougher than in insularis. Length 85 mm. 

 It often reaches a much" larger size, length 190 mm. or more. 



Haiti, in the mountains north of Lake Assuei, on the trail to 

 Las Cahobas, W. W. Webster; Arrondissement de Las Cahobas,. 

 G. Roumain; also south of Thomonde, Lloyd B. Smith. Occurs in 

 extensive beds composed almost wholly of oysters. 



Type No. 1308, A. N. S. P. 



Ostrea sculpturata osculum n. subsp. PI. 6, figs. 2, 2a. 



A small oyster of rounded or subtriangular shape, nearly equilateral. 

 The umbonal half is more or less obviously cuneate in outline, with 

 crenulated submargins; the opposite (basal) border is broadly rounded 

 and extremely sinuous, typically having two deep, angular plications 

 in each valve. The lower valve has a very shallow beak-cavity, the 

 flatter upper valve none. The adductor impression is strongly 

 lateral in position. Beaks are rather short and oblique, nearly equal 

 in the two valves. Length 42.5, width 39, cham. 37 mm. 



Some examples are flatter, with less emphatic and fewer plications. 

 It is certainly not identical with the recent 0. megodon. It differs 

 from 0. sculpturata by the reduced number and large size of the folds. 



Type No. 3037, A. N. S. P. 



