TERTIARY MOLLUSCA. 117 



simple threads; 1 row of high, pointed nodes convex anteriorly, concave poste- 

 riorly, forming a coronation adj acent to the suture. Outer lip and canal broken. 

 Length of fragment of 10 whorls, apex and part of anterior canal missing, 

 85 mm. ; diam. at decollation 7 mm. ; diam. of body whorl, 37 mm. 



This species is readily distinguishable from others of the mid- 

 American region by its large size and peculiar sculpture. 

 Locality. Crocus Bay, Anguilla, station 6965, Vaughan. 

 Geologic horizon. Oligocene. 

 Type.U. S. Nat, Mus. No. 166985. 



Cerithium species. 



Casts of a large Cerithium were obtained by Vaughan on the north- 

 west side of St. Jean Bay, St. Bartholomew, at stations 6905 and 6925. 

 A smaller species retaining the silicified shell, which shows imperfectly 

 the original sculpture, was collected at station 6897, a point between 

 Anse Ecaille and Anse Lezard. 



Geologic horizon. Upper Eocene. 



Cerithidea? anguillana, new species. 

 (Plate 3, Figures 10 a, b, 11, 12 a, 6.) 



The following is a description of this species: 



Shell slender; axial sculpture of numerous small, rounded ribs, about 15 to 

 the whorl, extending across the whorl, and feeble varices at intervals of about 

 three-fourths of a whorl; spiral sculpture of fine and coarser rounded threads, 

 thickened a little on top of the ribs; middle portion of whorl nearly flat, with 

 3 or 5 coarse threads separated by two or more finer ones; margins of the 

 whorls sloping to the moderately impressed suture and covered with fine 

 threads, with one coarser thread adjacent to the suture. 



Length of fragment of about 6 whorls, 19.5 mm.; width of largest whorl, 

 8.2 mm. 



Two young shells, probably of this species, show that the axial costse 

 do not extend to the base of the body whorl, which is ornamented with 

 fine, impressed, revolving lines. 



Locality. Crocus Bay, Anguilla, station 6965, Vaughan. 



Geologic horizon. Oligocene. 



Type. U. S. Nat. Mus No. 166991. 



Hemisinus costatus, new species. 

 (Plate 3, Figures 1 a, b.) 



The following is a description of this species : 



Shell long, slender; whorls moderately convex; suture deeply channeled. 

 Sculpture of strong axial or slightly protractive costse, 14 per whorl, termi- 

 nating abruptly at the first spiral line behind the suture, and 9 or 10 fine 

 revolving threads on whorls of spire and 3 additional strong threads and 

 several finer ones on base of body-whorl. Whorls coronated by a row of weak 

 nodes at the intersections of the most posterior thread with the costae. Aper- 

 ture oval; peristome incipiently channeled anteriorly. 



Length of fragment of 3| whorls, 20.6 mm.; length of body-whorl, 10.6 

 mm.; diameter of body-whorl, 7.5 mm.; length of aperture, 5.3 mm. 



