1895. rUOCEEDINGS OF THE NATIONAL MUSEVM. 45 



eartliy or porcelanous; the operculum like that of Sicjaretus. Type, 

 Adeorhis depressus, Jeffreys.' 



8i()aretUH prohlematicus and Gibbula mitis of Desliayes, from the 

 Paris basiu Eocene, appear from the figures to be referable here. The 

 Cretaceous species, upon which (ryrodes was founded, are considerably 

 larger, and the sutural sulcus, though not absolutely constant, gives 

 them a different asi)ect. There are several Tertiary and one or two 

 recent sj)ecies which belong to the subgenus as restricted. 



GYRODES (GYRODISCA) DUPLINENSIS, new species. 



Shell small, with a small glassy nucleus and somewhat more than 

 three whorls, the last much the largest; the nucleus primiinent above 

 the rather depressed spire; whorls rounded, suture very deep; base 

 rounded; uml)ilicus wide, its border hardly angular; scul})ture of 

 numerous, tlexuous, siibequal, regular, transverse, lamellar riblets, with 

 wider, faintly si)irally striate interspaces; aperture large, very oblique, 

 pointed above, rounded below, not interrupted by the preceding whorl; 

 lip simi»le, sharp, rather tlexuous, the inner one receding. Width, 3.6; 

 height, 2.7.5 mm. 



Upper Chesapeake Miocene of Magnolia, Dui)lin County, North 

 Carolina, Burns. 



TyjJe.—^o. 114430, U. S. N. M. 



This species differs from most of those belonging to the subgenus by 

 the obsolescence of the umbilical angle, though this may be, and prob- 

 ably is, an individual rather than a specific characteristic. 



Genus UMBONIUM, Link. 

 UMBONIUM (SOLARIORBIS) FLORIDANUM, new species. 



Shell small, depressed, three-whorled, with a smooth, glossj- nucleus, 

 the subsequent whorls deiu'essed and tricarinate; one carina is at the 

 periphery, oiieon the base, and the least i)iominei!t between the suture 

 and the i)eriphery; the latter fails on the last i)art of the last whorl, 

 and is more or less nodulous or undulated by faintly elevated but dis- 

 tinct radiating ridges, which begin weak, are strongest on the keel, and 

 die out before reaching the periphery; the base shows radiating ridges, 

 rather stronger than those on the spire, but which do not creimlate the 

 strong basal keel; umbilicus moderate, with a single spiral thread above 

 the lingular margin; aperture entire, oblique, the edge simple, but 

 modified by the intersection of the keels. Diameter, 1.0; height, 1 mm. 



Habitat. — Pliocene of the Caloosahatchie beds, Dall. 



Type.—^o. 113590, U. S. N. ]\I. 



This very small species appears adult, and has a rather solid and 

 strong shell. 



1 Jeffrey's, Proc. Zool. ,Soc. LoncL, 1885, p. 41, \)\. iv, figs. 8, 8a; Dall, Blake Gastr., 

 p. 298, 1889. 



