﻿JURASSIC AND TRIASSIC BRACHIOPODA. 



89. Terebratula ventricosa, Hartmann{?). Sup., PL XV, figs. 10, 11. 



Terebratula ventricosa (Hartmanri). Zeiten. die Versteinerungen Wiirtembergs, 



p. 52, pi. xl, figs. 2 a, b, c, 1830. 



— — Quenstedt. Petrefactenkunde Deutschlands, Brachio- 



poden, pi. xlix, 1871 . 



— — E. Deslongchamps. Pa!. Fran^. Brachiopodes Juras., 



p. 260, pi. lxxiii— lxxvi, 1862. 



Spec. Char. — Longitudinally oval or ovate, longer than wide, deepest posteriorly, 

 valves almost equally convex. Dorsal valve uniformly convex to about the middle of its 

 length, when a more or less biplicated fold rises gradually and produces a flattened or 

 more or less deeply biplicated wave in front. Ventral valve almost uniformly convex, or 

 with a slight mesial elevation towards the front, margined on either side by a rounded 

 groove which corresponds to the biplication in the opposite valve ; beak incurved and 

 truncated by a circular foramen. Surface smooth, marked only with concentric lines of 

 growth. Proportions variable ; an English example measured — 



Length 1 inch 10 lines ; width 1 inch 3 lines j depth 1 inch 1 line. 



05s. — I do not know very much about this species, which seems to vary to a 

 very considerable extent. Some examples present a uniformly convex fold in the 

 dorsal valve, which in many others is more or less deeply biplicated. In this last-named 

 condition the shell might be almost confounded with some specimens of several 

 biplicated species, such as T. perovalis, T. intermedia, T. Phillipsii, and others, for 

 which distinctive characters are so difficult to find or express. 



Mr. Deslongchamps adds to his description of this species a long synonomy, among 

 which he places the shell to which I gave the name of T. Buckmanii, but I cannot 

 admit this identification when I compare it with German and French examples, and 

 figures of Hartmann's, or Zie ten's shell. He adds that T. ventricosa can be at once 

 distinguished from its congeners by its shell-structure, and by the fine longitudinal 

 radiating lines of which traces can be observed on well-preserved German and 

 French specimens,- — a character, however, which he does not fail to admit, may be 

 equally noticed in many other species of Terebratula, Waldheimia, &c. 



The presence of Zieten's species in British strata was noted, I believe, for the first 

 time, by Mr. Walker, in the 'York Herald' for the 9th of October, 1875, as well as in 

 the * Geol. Mag.,' vol. ii, 2nd ser., p. 572, 1875. None of the British examples that 

 have come under my observation, if they really belong to the German type, have attained 

 the dimensions of those found upon the Continent. 



Position and Locality. — Mr. Deslongchamps informs us that the shell is abundant in 

 many French localities, and occurs in the zones of Amm. Humphresianus and Parkinsoni 



