JURASSIC AND TRIASSIC BRACHIOPODA. 193 



seen exceeded 1 inch 2 lines in length, by 1 inch 4 lines in breadth, and 1 inch 

 in depth, and none of them assumed the shape and character of the full-grown 

 Rh. inconstans. Therefore, when taken as a whole, the Abbotsbury fossil presents differ- 

 ences sufficiently marked as to lead us to consider it specifically distinct. The difficulty 

 then arises as to its identification with some of the described species, and I have 

 experienced the same perplexing uncertainties expressed by M. de Loriol while describing 

 his Rh. pinguis (?) from the Corallian Limestone of the Mont des Boucardes in the 

 Boulonnais. I consider it advisable to adopt Romer's name pinguis for the species, and 

 to make use of Etalon's term pectunculoides for the variety with large ribs, that occurs 

 at the Mont des Boucardes, near Boulogne-sur-Mer. 



181. Rhynchonella pinguis, Romer. Sup., PI. XXVI, fig. 7. 



Terebratula pinguis, Romer. Petref. des Nordd. Ool. Geb., p. 41, pi. xi, fig. 15, 



1836. 

 — corallina, Ley. Statistique Geologique du Dep. de l'Aube, p. 10, 



figs. 16, 17, 1846. 

 Rhynchonella pinguis, JEtalon. Corallien du Haut-Jura, p. 155, 1859 (no figure). 



— — J. Thurman et A. Etalon. Lethaea Bruntrutana, p. 290, 



pi. lxii, fig. 5, 1861. 



— i — Be Loriol. Desc. Geol. et Pal. des etages sup. Jur. Haute- 



Marne, p. 417, pi. xxvi, figs. 4—12, 1872. 



The first question to be solved is, what is Romer's Rhynchonella pinguis. If we 

 refer to the figure of his species, we find that it represents a shell measuring about 9 

 lines in length, by 10 in breadth, and varying in depth from 3 to 7 lines, and 

 that it is almost circular, with hardly any appreciable fold or sinus. The beak is small 

 and incurved, with a circular foramen under its angular extremity, margined, and 

 separated from the hinge-line by two deltidial plates. The surface of each valve is covered 

 with from twenty to twenty-two small, almost equal-sized, radiating ribs on each valve. 

 These are the characters of the shell figured by Romer, and they are apparently applicable 

 also to Rhynchonella corallina of Leymerie : but both varied, no doubt, very much ; and if 

 we had a number of species before us, we should in all probability, obtain larger 

 individuals, and some likewise with the fold and sinus more defined, leading us by 

 insensible passages in form to the larger variation in shape, for which, at least provision- 

 ally, we retain the varietal designation of pectunculoides of Etalon. 



A few small specimens found at Abbotsbury seem to agree with Romer's figure of 

 Rh. pinguis, but the larger number, and perhaps all of them, partake more of the 



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