TROCHUS. * 75 



The following variations have received names. They are scarcely 

 distinct enough to be called varieties, for typical examples of all 

 three occur in one of the sets before me. 



Var. nigrescens Requien. (-brunnea Req.,-monochroa Mouts.) 

 Color uniform brown or blackish, without white flammules. 



Var, rosea Mouts. (pi. 19, fig. 13.) Rose-colored, with or without 

 white markings. 



Var. Candida Monts.'(pl. 19, fig. 12.) Entirely white. This and 

 var. rosea are abundant in the Gulf of Gabes, Tunis. (See Moll 

 du Roussillon, p. 413.) 



T. KRAussi Philippi. PI. 10, figs. 8, 9. 



Shell umbilicate, conoid, moderately thick; whorls 5, convex, 

 separated by canaliculate sutures; first whorls eroded, whitish, the 

 rest roseus, cinereous or brownish, oi'nameuted Avitb a few radiating 

 white streaks, spirally granose-lirate, tlie lirse 6 on the penultimate 

 whorl, the fifth larger, more prominent, simulating a carina ; last 

 whorl angulate, plano-convex beneath, concentrically cingulate, the 

 cinguli granose, about 7, the interstices sometimes bearing concentric 

 liruke; aperture rhomboidal, lip within thickened, sulcate, basal 

 margin crenulate ; columella tuberculose, above twisted plicate, be- 

 low obsoletely truncate ; umbilical area white spirally plicate, mar- 

 gin crenulate; parietal callous thin, wrinkled. 



Alt. 19, diam. 12 mill. (Fischer.) 



TF. Coast of Africa. 



Monodonta kraussi Philippi, Zeltschr. f. Mai. 1846, p. 100. — T. 

 kraiissi Phil. Conchy I. Cab., p. 82, 1. 14, f 14. — Fischer, Coq. Viv., p. 

 377, t. 114, f 4. 



Allied according to Dr. Fischer, to T. cruciatus L. but distinguished 

 by the less rounded whorls, shallower sutures, closer spiral lirje, 

 smaller tooth at base of columella and by the well developed um- 

 bilical crenulations. 



T. JussiEUi Payrandeau. PI. 11, figs. 36-38 ; pi. 19, fig. 11. 



Shell depressed-globose conic, umbilicate, polished, shining, black- 

 ish, olive or purplish brown, uuicolored, dotted or tessellated with 

 white, often with shoit flames of white beneath the sutures and 

 always more or less marked with white around the umbilicus ; spire 

 conical, sutures simple, impressed ; whorls 5 to 6, convex, the upper 

 surface marked with obsolete, frequently almost imperceptible line, 

 the interstices between them finely spirally striate ; base smoother, 



