MUSEUM OF COMPARATIVE ZOOLOGY. 337 



round elevation on the inner side. It is thinner here than elsewhere, and 

 weathered opercula have always a central perforation. 



The minute variegated Liotia (Arene) miniata of the West Indies has a 

 similar operculum, as does A. tricarinata Stearns. L. Briareus Dall has an 

 operculum like that described by Arthur Adams, almost wholly horny, exter- 

 nally hispid, with a row of beady granules on each whorl of the operculum. 

 In Liotia Bairdii the operculum seems to want even the granules, and to be 

 wholly horny. 



The sculpture is of two kinds; one, a fine shagreening which generally covers 

 the whole surface and is only visible under a lens; it seems to be invariable 

 in the same species. The other sculpture consists of spiral ridges, or of scales, 

 spines, knobs, etc., which are very inconstant and not characteristic even of 

 the species in some cases. An examination of the dentition shows it closely 

 related to that of Delphinula, as might have been expected. 



The umbilicus varies from barely pervious (L. Biisii Dkr., etc.) to nearly 

 plane in the genus, and from perforate to wide in different individuals of the 

 same species, much as with some of the small Gibbulas. The elevation of the 

 spire often differs considerably in different specimens of the same species, and 

 the color markings are admitted on all sides to be as variable as they are bright 

 and elegant. 



The species of our southern coast and the Antilles appear to be as fol- 

 lows : — 



Liotia, Section Arene. 



Liotia Briareus Dall. Liotia cruentata Miihlf. 



Liotia Bairdii Dall. Liotia variabilis Dall. 



Liotia Biisii Dunker. Liotia tricarinata Stearns. 

 Liotia miniata Dall. 



Subgenus Lippistes. 

 Lippistes acrilla Dall. Lippistes amabilis Dall. 



Subgenus Laxispira. 

 Laxispira nitida Verrill. 



" Circulus" formosissimus Brugnone of the Mediterranean is also a Lippistes, 

 allied to L. acrilla. 



" Delphinula " tuberculosa Orbigny (tuberculata on the plate, which was pub- 

 lished first, Trochus Schrammi of Fischer according to the Beau catalogue) is 

 almost certainly a Fossarus. C>/clostrema Schrammi Fischer may perhaps 

 prove to be an extremely young Lippistes. 



