MUSEUM OF COMPARATIVE ZOOLOGY. 359 



sis of Helicina did not mention any type (Prodr., 1799). There is no doubt, 

 however, that Link's name, which was properly defined, takes precedence. 



This genus has hitherto been unknown from the Antilles, the species referred 

 to it belonging to Teinostoma and allied groups. I have therefore much 

 pleasure in introducing here a description of a genuine Umbonium, dredged 

 by the Fish Commission in the Antillean region, near the Florida reefs, aiid 

 obtained by the Blake near Havana. 



Umbonium Bairdii n. s. 



Plate XXI. Figs. 6, 6 a. 



Shell small, depressed conic, white, polished, externally porcellanous, in- 

 ternally slightly nacreous; nucleus globular, dextral; whorls five or more. 

 Radiating sculpture of occasional faint impressed incremental lines; spiral 

 sculpture of occasional microscopic striae, and a single strap-like band ap- 

 pressed to the suture, and bearing numerous flattish squarish nodules or 

 elevations, which coronate the whorls ; periphery rounded, base rounded, de- 

 pressed in the centre, which is nearly filled with a mass of white callus having 

 a very finely granular surface. Aperture ovate, margin simple, thin, oblique. 

 Alt. of axis, 3.5; max. alt. of shell, 4.0; max. diam. of base, 5.0 mm. 



Habitat. Florida reefs, in about 200 fms., coral bottom, U. S. Fish Com- 

 mission, 1886. Yucatan Strait, 640 fms., Blake Expedition. 



The specimen is not quite adult. The granular surface of the callus is com- 

 mon to the young of other species, and is lost in the adult. The soft parts 

 were absent. It is named in honor of the late Prof. S. F. Baird, U. S. Fish 

 Commissioner. 



Genus VITRINELLA C. B. Adams. 



A group of small shells, several forms of which were comprised by C. B. 

 Adams under the name of Vitrinella in February, 1850, still remain in need of 

 further elucidation. As originally constituted, the genus was heterogeneous 

 and no type was named. In 1853, A. Adams (P. Z. S. 1853, p. 183) described 

 a genus Teinostoma (type T. politum Adams), of which a species had been re- 

 ferred to Vitrinella by C. B. Adams in his Panama catalogue. Another some- 

 what peculiar species was described by C. B. Adams as " Nerithia?" anomala, 

 and was afterward referred to a section of Teinostoma by A. Adams under the 

 name of Calceolina. At the same time (P. Z. S. 1853, p. 189) Messrs. H. & A. 

 Adams described a genus Ethalia for minute glassy shells related to Teinostoma, 

 but having an umbilical pit or perforation, no large polished callus, but the 

 anterior end of the columella lip thickened and squeezed down near to and 

 sometimes over the umbilical region. This genus Ethalia would include two 

 species of the five originally described as Vitrinella by C. B. Adams. This 

 would leave to bear the name of Vitrinella such forms included in the original 



