GASTEROPODA. 27 



1. Cassidaria bicatenata. /. Soio. Tab. IV, fig. 5, a — b. 



Cassis bicatenatus. /. Sow. Min. Con. t. 151, 1824. 



Cassidaria bicatenata. S. Wood. Cat. of Crag Shells in Ann. and Mag. Nat. Hist. p. 538, 1842. 

 — Kysf. Coq. foss. de Beige, p. 565, pi. 46, fig. 6, 1844. 



C. Testa ovato-ventricosd, transversim sulcata; sulcis depressis, lonc/itudinaliter 

 decussatis; anfractihus comexis, subcarinatis ; carinis tuberculosis ; labro incrassato,intus 

 obscure dent at o. 



Shell ventricose, ovate, sulcated or ridged; obscurely decussated; volutions 

 tumid ; last whorl large, inflated, upper part subcarinated and tuberculated ; outer 

 lip thickened, faintly dentated ; inner lip broad and expanded ; columella finely and 

 irregularly striated. 



Axis, 4 inches ; transverse diameter, nearly 3 inches. 



Locality. Cor. Crag, Ramsholt and Gedgrave. 



Red Crag, Sutton, Bawdsey, and Felixstow. 



This handsome shell is at present exceedingly rare in both formations. Specimens 

 have been occasionally washed up on the beach at Felixstow, along with Valuta 

 Lamberti, apparently thicker and stronger than the generality of shells from the Red 

 Crag, which Mr. Charlesworth (Mag. Nat. Hist., 1837, p. 38) thinks were from a 

 deposit posterior in age to that formation. 



The subangulated appearance on the upper part of the volution is produced by a 

 double row of nodules upon the ridges, the upper one of which is the most prominent. 

 These nodules may be traced upon two or three of the ridges, becoming more obscure 

 as they descend upon the body whorl. The outer lip of one specimen is much thick- 

 ened and a large callus deposited upon the body of the shell, forming a distinct sinus 

 at the upper part of the aperture. The canal is rather shorter than in the generality 

 of shells in this genus, but is not deep and reflected like that in Cassis. This shell 

 thickens its outer lip at irregular periods of growth, leaving thereby obtuse varices 

 visible upon the spire. This is also the case in many of the Helmets. Specimens 

 from the English Crag attain a magnitude considerably beyond that figured by 

 M. Nyst ; one of mine exceeds it twofold in linear dimensions. 



Nassa,* Lam. 1801. 

 , BccciNUM (spec.) Linn. 



Gen. Char. Shell ovate, turriculate or conoidal ; spire generally longer than the 



.aperture; apex mostly acute; exterior grooved, striated, granulated, or tubercidated, 



sometimes smooth ; inner lip largely expanded, with a tooth-like projection at the base 



of the columella, and sometimes a tooth upon the left lip, at the upper part of the 



* Nassa is the name of a kind of net, for catching fish, made of twigs like an eel-pot ; probably in 

 allusion to the generally reticulated surface of these shells. 



