VOL. XIV 

 1891 



'] PROCEEDINGS OF THE NATIONAL MUSEUM. 181 



is livid brown and white, the inner lip in the anterior third of the canal 

 is erect and separate from the si phonal fasciole. It was kindly lent by 

 the owner for inspection. 



We are indebted to Mr. J. J. Rivers, curator of the biological collec- 

 tion of the University of California, for the opportunity of examining 

 and figuring the original type specimen of Trophon triangulatm in order 

 to complete our account of the species. This young shell difters from 

 the adult in its whitish color, and in having one or two more varices to 

 the whorl. The proportional length, as in all young TrophonSj between 

 the spire and the last whorl difters somewhat from the adult. The spec- 

 men contains the operculum, which is yellowish, subtranslucent, and 

 apically pointed like that of Chrysodomus. It measures 11.5 by C.3 milli- 

 metres. The nucleus is small, smooth, and of two whorls. It resembles 

 the young of T. Gunneri, but has a shorter and acuter spire and narrower 

 canal. It is represented by figure 3 on plate V. 



Trophou cerrosensis, sp. nov. 

 (Plate V, Figs. 5, 7.) 



Habitat: Off Cerros Island, Lower California, in 12 to 48 fathoms, 

 mud and sand, at Stations 2831 and 2831; U. S. Fish Commission. 



Shell of moderate size, thin, elongate, with seven whorls and eight 

 to ten sharp, thin, elevated varices, each produced into a sharp, recurved, 

 guttered spine at the shoulder ; color, white to straw color, with blushes 

 of warm brown ; transverse sculpture of fine lines of growth ; spiral 

 sculpture of low, rounded bands, with narrower interspaces, which 

 faintly crenulate the varices and outer lip ; behind the shoulder these 

 are absent; nucleus small, translucent, smooth, and polished, of one and 

 a half whorls ; subsequent whorls flattened behind the shoulder, slightly 

 constricted at the base; canal rather long and wide, flexuous, with a 

 marked fasciole; lip thin, pillar with a moderate whitish callus; throat 

 white, without lirte ; operculum dark brown, rather rounded. Longi- 

 tude of shell, 38; maximum latitude, 25; maximum diameter of aper- 

 ture, 9 millimetres. 



This beautiful form most resembles the young of Chorus Belcheri, 

 which is much more solid, with fewer varices, and strongly reticulately 

 sculptured. The figure of T. cerrosensis, given herewith, is turned so 

 that the aperture is obliquely presented, so as to show the arch of the 

 pillar; if it had been given in full front view the aperture would have 

 seemed more rounded and wider. 



This seems to belong to the same group as T. triangulatus, but is a 

 much smaller and more delicate species. A marked characteristic is 

 the difference of sculpture between the part of the whorl in front of and 

 that behind the shoulder. 



