364 PROCEEDINGS OF THE ACADEMY OF [April, 



Two other specimens measure as follows: 

 Length 14.9, alt. 14.8, semidiam. 4.9 mm.; hinge-teeth 8.9. 

 " 14.0, " 12.5, " 3.9 " " " 7.9. 



Glycymeris oanalis n. sp. PI. XXVIII, fig. 10. 



The subcircular shell is a little higher than long, solid, equilateral, 

 with nearly straight, contiguous beaks, the ligamental area being 

 extremely narrow and short. Sculpture of 33 strong, rounded ribs, 

 separated by linear grooves, and obsoletely marked with rather 

 regular concentric growth-stria? . Tooth-row strongly angulated in 

 the middle, with 10 teeth on each side. Inner margin crenulated with 

 about 20 strong "teeth," the upper margins not crenulated. 



Length 14.5, alt. 15.1, semidiam. 4.6 mm. 



Described from several valves, on which we count 30, 31, 32 and 

 33 ribs. This species has a close resemblance to G. pectinata (Gmel.) 

 of the Antillean fauna, which differs by having wider sulci between 

 the ribs, and by having an area of smaller ribs on the anterior end, 

 while in canalis they decrease gradually in size. 



Glyoymeris acuticostata Sowb. 



Pectunculus acuticostatus Sowb., Journ. Geol. Soc. Lond., VI, 18-49, p. 53, 

 PL 10, fig. 13 (Santo Domingo). 



Typical, agreeing with Santo Domingo and Jamaican specimens. 



PECTINIDiE. 

 Pecten CEquipecten) effossus n. sp. PI. XXVIII, figs. 4, 6. 



An orbicular, equilateral, compressed shell, resembling P. scissuratus 

 Dall. The length and diameter are nearly equal, the ears subequal, 

 the left valve nearly flat, the right one more convex. A left valve 

 has 17 ribs, as wide as the slightly concave intervals. Each rib has 

 the shape of an inverted V, but with rounded ridge, and a thin longi- 

 tudinal lamella in the middle of each lateral slope, these lamella? define 

 furrows which terminate in incisions at the edge. The whole surface 

 is finely sculptured with delicate concentric threads, subregularly 

 and not closely spaced. These threads are arched downward in the 

 intervals. Ears marked with several narrow radial riblets and con- 

 centric growth-threads. Length 1 1 .2, alt. 11 mm. The right valve of a 

 large shell, alt. about 19 mm., has similar sculpture, except that the 

 ribs are larger. The interior is deeply furrowed in both valves. 



The specimens of P. scissuratus in Gabb's Santo Domingo collection 

 (PI. 28, figs. 2, 5; alt. 27, width 27.5 mm.) differ from the above- 

 described form by having the concentric threads crowded and crimped 

 in the intercostal spaces and by having much better developed lam- 



