Cretaceous and Tertiary Ctrripedes. 183 



Description of Valves. The valves of this species have the 

 ridj^es terrainating each zone of growth much raised and 

 with stec|)ly sloping sides, the longitudinal ridges also being 

 raised and prominent. 



Carina (fl. Vli. Hg. 9) semicylindrical, widening gradu- 

 ally from the apex to tlie basal margin, moderately bowed 

 inwards, strongly convex transversely, not carinate, basal 

 margin slightly concave. Outer suiface ornamented with a 

 number of prominent transverse ridges crossed by longitu- 

 dinal ridges, which present a goffered appearance where tlicy 

 meet. The apical portion projected freely for more than a 

 third the length of the valve, and this part is marked with 

 growth-lines, w^hich extend from the basal angles and meet 

 in an acutely rounded angle helow the apex ; the inner 

 lateral edges are somewhat thickened for about one-fourth 

 the width of the valve. 



Rostrum {^\. VII. fig. 5) semiconical, smaller and propor- 

 tionally wider than the carina, widening rapidly from the 

 apex to the basal margin, considerably incurved, strongly 

 convex transversely, basal margin slightly convex. Outer 

 surface with ornament similar to that of the carina. The 

 apical half projected freely, and on the inner surface this 

 part is marked with growth-lines that extend from the basal 

 angles and meet in a rounded angle below the apex ; the 

 inner lateral edges are somewhat thickened to about ont- 

 third the width of the valve. 



Scutum (PL VII. fig. 6; PI. VIII. fig. 6) subtriangular, 

 strongly convex transversely, apex acuminate and strongly 

 curved towards the terga; occludent margin usually strongly 

 convex ; basal margin almost straight, about half the length 

 of the occludent margin, and making with it an angle slightly 

 above 90'^; tergo-lateral margin usually strongly concave in 

 its upper part, and varying from straight to strongly convex 

 in its lower part, which forms nearly a right angle with the 

 basal margin. Basi-lateral angle generally sliglitly produced, 

 and obliquely truncated, the projection being formed by the 

 apico-basul lidge. This ridge is a conspicuous feature, and 

 extends from the apex in a slightly curved line, much nearer 

 to the tergo-lateral margin. It is much raised, flat-topped, 

 has perpendicular sides, is wider in most valves than a zone 

 of growth, in some much wider, and even wider than the 

 tergo-lateral portion of the valve (see PI. VIII. fig. 6). It is 

 formed of longitudinal ridges varying in number from two 

 to five. An almust imperceptible ridge extends from the 

 apex almost parallel to the upper part of the tergo-lateral 

 margin, and from this ridge the valve is strongly rounded 



