380 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



which is rounded, with the dorsal slope rather flat; posterior end attenu- 

 ated; hinge normal, the posterior left cardinal obscure, thin, con- 

 solidated with the nj^mph; internal margins tangentially sulcate; pallial 

 sinus deep, narrow, somewhat rounded in front. Length 14; height 

 10.5; diameter 7 mm. 



Type locality.— E^gmont Key, Florida. Cat. No. SIlOO, U.S.N.M. 



The shell is marked b,y line concentric lines of growth, and by a 

 few, irregularly distributed, stronger concentric sulci, which become 

 evanescent toward the middle of the disk. 



TIVELA ABACONIS, new species. 

 Plate XIII, fig. 3. 



Shell small, subtranslucent, deep rose color at the beaks and in the 

 middle of the disk, becoming paler toward the margins; beaks high, 

 pointed, subcentral; shell moderately inflated, the ends rounded, the 

 base gently arcuate; surface polished; hinge delicate; the teeth small, 

 three cardinals in each valve, the anterior lateral elongate, thin, dis- 

 tant; pallial sinus short, wide, rounded; length, 11; height, 8.2; 

 diameter, 6 mm. 



lyp<i locality. — Abaco, Bahamas, I. Greegor. Cat. No. 103551, 

 U.S.N.M. 



The shell is smaller, more delicate, more equilateral, and of a difl'er- 

 ent color and texture from T. trigondla Lamarck, which is the only 

 species comparable with it and which is white and opaque with a con- 

 spicuous periostracum. 



TIVELA NASUT \, new species. 

 Plate XII, fig. 2. 



Shell of moderate size, solid, nearly equilateral, somewhat rudely 

 concentrically striated, with a reddish-brown polished periostracum; 

 shell substance white, wdth numerous pale purple radii, the dorsal 

 posterior margin near the end dark brown within and without; beaks 

 pointed, dorsal slopes nearly straight; luiuile impressed, defined b}^ a 

 distinct incised line; anterior end rounded, posterior end narrower, 

 almost rostrate; hinge solid, with four cardinals, the anterior lateral 

 lamelliform, prominent; pallial line with a short, small, rounded sinus. 

 Length, 32.5; height, 25; diameter, 17 mm. 



Tyjje locality. — Santa Marta, Colombia; Baker. Cat. No. 153377, 

 U.S.N.M. 



By its rudely striated surface and produced posterior end, this 

 seems to ditter from the other Antillean forms. 



