﻿72 BRITISH FOSSIL TRIGONI^E. 



cord-like costae, is without the small anteal series. In the general lengthened outline it is 

 also not without some resemblance to T. Pellatl ; but they differ^ in all the essential 

 features of ornamentation. 



Stratigraphical position and Locality. T. Leclcenbyi ranks as one of the most rare of 

 the Trigoniae. I am not aware that more than four entire examples of single valves have 

 been procured, and fragments of a few others ; all are more or less flattened from 

 vertical pressure, and only portions of the test remain ; but the characters of the surface 

 are sufficiently well preserved. The rock is a dark grey, highly micaceous, thin-bedded, 

 shaley sandstone, a member of the stage which may be provisionally termed Supra-liassic, 

 and according in position with the ///?-e«szs-beds of the Cotteswold Hills ; it is associated 

 with some of the characteristic fossils of that stage, and more especially vvith Terebratula 

 trilineata, Y. and B. It has been procured only over a small area in shore-beds covered 

 by the tide at high water, between Blue Wyke and the Peak, near Robin Hood's Bay, 

 upon the coast of Yorkshire. The geological position is therefore higher than the Alum 

 Shale or the zone of Ammonites communis, and lower than the stratum with Lincjula 

 Beanii. 



Trigonia Carrei, Mun.-Chal. PI. XII, fig. 1. 



TiiiGONiA Caurei, Mimier-Chalmas. Note sur quel. esp. iiouv. du genre Trigonia, 



Bull. Soc. Linu. de Normandie, 1865, vol. i.x. 



— — De Loriolet Pellaf. Mon. Paleont. et Geol. de I'etage Portlandien 



des env. de Boulogne, 1SG6, pi. viii, fig. .5. 



— — Hibert. Terr, jurass. du Boulonnais, Bull, de la Soc. Geol. France, 



1866, 2 ser., t. xxiii, p. 216. 



Shell ovately trigonal, moderately convex ; umbones sub-anterior, elevated, obtuse, 

 and erect; anterior side short, its border somewhat truncated, but having its lower 

 portion curved elliptically with the lower border ; cardinal border moderately lengthened, 

 straight, sloping obliquely, and curved suddenly with the posterior extremity of the area. 

 Escutcheon excavated, its superior border raised. Area narrow, flattened, conspicuously 

 bi-partite ; the plane of its surface forms a considerable angle with the other portion of the 

 shell ; it is bounded by two well-defined tuberculated carina} ; the tubercles upon the 

 marginal carina are more especially large and distantly arranged ; there is also a line 

 of small tubercles bordering upon the mesial furrow ; the transverse plications upon the 

 area are irregular and not conspicuous. The other portion of the surface has a series of 

 large elevated varices, about twelve in number, which curve downwards from the 

 carina, occupying more than half the costated surface ; each row has about nine depressed 

 nodes ; the lower extremities of these varices meet the posteal extremities of a much 

 smaller anteal series, which are nodose, short, and nearly horizontal in their direction. 



