19 i PROCEEDINGS OF THE NATIONAL MUSEUM vol. 93 



deep. There is a rather sharp keel around the moderately narrow 

 umbilicus. Aperture ovate, slightly oblique; outer lip simple, eolu- 

 mellar portion narrowly reflected and curving gently into the callus 

 on the parietal wall. Operculum thin, ovate, transparent: nucleus 

 excel it ric. 



The type, U.S.N.M. No. 536048, measures: Height, 2.4 mm.; 

 breadth, 1.6 mm., and was collected on Bonefish Key. Florida Keys, 

 by Dr. B. R. Bales. 



Genus RISSOELLA Gray, 1847 

 Phycodrosus, 3 new subgenus 



Differs from Rissoella s. s. by being more broadly ovate and in 

 being umbilicated, the umbilicus surrounded by a sharp keel. From 

 ./. freysina Thiele, 1925, it differs in being more slender and having 

 a narrower keeled umbilicus. 



Type: Rissoella (Phycodrosus) ca/'ibaca, new species. 



This is the first record of the family Rissoellidae from the West 

 Atlantic and also the first species from the tropical Atlantic. I am 

 recognizing Jeffreysina as a distinct genus because of its turbinate 

 shape and broad umbilicus. 



RISSOELLA (PHYCODROSUS) CARIBAEA, new species 



Plate 20, Figure 7 



Shell minute, broadly ovate, transparently glassy; whorls 4%, 

 convex, suture shallow, surface smooth, except for very fine hairlike, 

 irregularly and distantly spaced, growth lines. Umbilicus narrow, 

 surrounded by a sharp keel. Aperture ovate-semicircular. Outer 

 lip thin, simple: inner lip reflexed at the base, the columellar portion 

 making a straight line with the callus on the parietal wall. Oper- 

 culum thin, transparent, semicircular, nucleus near the center of the 

 inner edge, surrounded by concentric growth lines. Central radial 

 lamella faintly visible from the exterior. 



The type, U.S.N.M. No. 536046, measures : Height, 1.5 mm. : breadth, 

 1 mm. It was collected by Dr. Bales at Bonefish Key, Fla. 



Genus CREPITACELLA Guppy, 1867 



CREPITACELLA VESTALIS, new species 



Plate 20, Figure 13 



Shell relatively large, ovate, yellowish white. Nucleus consists of 

 not quite two bulbous glassy whorls. Postnuclear whorls 7, convex, 

 separated by a deep suture, sculptured with axial ribs and slightly 



5 $vkos, seaweod+ipififfos, dew. 



