126 GEOLOGY AND PALEONTOLOGY OF THE WEST INDIES. 



Neretina? grandis, new species. 

 (Plate 5, Figures 7, 8.) 

 The following is a description of this species: 



Shell large, rapidly expanding; younger whorls shouldered, older whorls 

 rounded; spire very low, largely covered by body-whorl; suture not impressed; 

 inner walls resorbed. 



Alt., about 32 mm.; width, 35 mm. 



The generic position of this species is puzzling. The resorption of the 

 inner walls of the shell, as shown in casts of the interior, ally it with the 

 Neritidse rather than with the Naticidse, to which it bears a superficial 

 resemblance. The young shell shows a rather close resemblance in 

 shape and size to some of the species of Neritina living on the west 

 coast of America, but the mature shell attained a length of nearly 8 

 cm., much larger than any of the known species of that genus. In size 

 and general appearance the species is not unlike the genus Velates of 

 the Eocene of the Paris Basin, but appears to lack the superficial 

 shelly layers which conceal the suture in that genus. 



The columellar lip in all the specimens at hand is concealed by the 

 hard matrix. 



Localities. — Anse Lizard and St. Jean Bay, St. Bartholomew, sta- 

 tions 6926 (type) and 6925, Vaughan. A cast of a species resembling 

 this in size and shape was obtained recently by me from the Ocala 

 limestone at the Holder phosphate mine, 5 miles southwest of Inver- 

 ness, Florida. 



Geologic horizon. — Upper Eocene. 



Type.— U. S. Nat. Mus. No. 167038. 



Planorbis siliceus Brown and Pilsbry. 



Planorbis siliceus Brown and Pilsbry, Proc. Acad. Nat. Sci. Phila., p. 212, plate 9, figs, la, 

 3a, 5a, 6a, 1914. 



The following is the original description of this species : 



"This is a species of the section Trop'corbis. The shell is rather thick, with 

 the periphery rounded, more convex towards the right side. The two sides 

 are about equal in width of the concavity, but that on the right side pene- 

 trates more deeply, being vortex shaped. The last whorl is rounded on this 

 side. On the left side the last whorl is subangular and the cavity is less 

 infundibuliform. 



"Diameter 3.5, greatest alt. 1.7 mm. 

 5 " " 2.1 " 



"This species belongs to a widely spread group of the modern tropical 

 American fauna." 



Locality.— Dry Hill Point, Antigua, station 6867, Vaughan. 

 Geologic horizon. — Oligocene. 

 Type.— Philadelphia Academy. 



