MUSEUM OF COMPARATIVE ZOOLOGY. 363 



where a single rounded riblet or carina bounds a somewhat concave lunate 

 space outside of the polished columella; outer lip thin, sharp, a moderate 

 callus on the body; pillar thick, polished; operculum translucent yellowish, 

 of about five turns ; aperture rounded, with a slight angle behind. Diam. of 

 shell, 4.0; of aperture, 2.0; height of shell, 3.0 mm. 



Habitat. Station 215, off St. Lucia, in 226 fins., coarse sand, bottom tem- 

 perature 51°.0. 



This little shell will not fit into any of the groups defined in the text-books, 

 resembling more than any other group the Rotellidce, from which it differs in 

 wanting the sutural fasciole, the nacreous layer, and the basal callus, as well 

 as in possessing an epidermis. It is remarkably solid for its size, and of a 

 peculiar opaque whiteness, like Mamma among the Naticidm. It is named in 

 honor of the respected Dr. Dillwyn, whose " Catalogue " is one of the most 

 careful and judicious works of the kind among the many which were published 

 between the tenth edition of the " Systema Naturae " and the epoch-making 

 " Histoire des Animaux sans Vertebres" of Lamarck. 



Genus CALLIOST03IA Swainson. 



CalUostoma Swainson, Malacology, pp. 218, 351, 1840. 

 Ziziphinus Gray, Synops. Brit. Mus., 1840. (No description.) 



There is no doubt that Swainson's name was defined in a proper manner, 

 and published, before the name published by Gray and ascribed to an old 

 manuscript of Leach. As the duplication of such a word as Ziziphinus has a 

 particularly obnoxious sound, and the practice is condemned by all nomen- 

 clators and all rules, there would seem to be no reason except the natural 

 perversity of human nature why any one who knows the facts should adhere 

 to Gray's name in preference to the other. The type is Trochus conulus L. 

 The nucleus appears to be either dextral or sinistral indifferently. 



Section CALLIOSTOMA s. s. 

 Not umbilicated. 



Calliostoma euglyptum A. Adams. 



Zizyphinus euglyptus A. Adams, P. Z. S. 1854, p. 38. Reeve, Mon. Zizyph., pi. iii. 

 fig. 17, 1863. 



Habitat. Off the eastern coast of America, in 15-50 fms., from North 

 Carolina to Florida, Texas, and Vera Cruz, Mexico. Fossil in Florida Pliocene. 



This fine species varies in color from dark rose to yellowish white, some- 

 times unicolor, sometimes variegated with whitish clouds radiating from the 

 invariably purplish apex. It was referred by Reeve to Tasmania, in error. 

 It is the commoner imperforate species of Florida, often collected by tourists, 



