﻿CRETACEOUS BRACHIOPODA. 



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Middle Neocomian at Acre House, near Tealby, in Lincolnshire; and of these good 

 examples may be seen in the Museum of the School of Mines, London, and in the Wood- 

 wardian Museum at Cambridge. 



It is a very abundant fossil upon the Continent. Very large examples occur in the 

 Hilsthon, Elligser Brinke Schist (Middle Neocomian of Elligser Brinke, near Delligsen, 

 Hanover), also in the Hils Conglomerate of Schoeppenstedt, iEselberg, and the Grosse 

 Vahlberg, Brunswick ; in the Marnes d'Hauterive, at Villers-le-lac, Cressier, Landeron, 

 Locle, Mont Saleve in Switzerland ; in the Middle Neocomian of Morteau (Doubs), of 

 Auxerre, Mozeroy (Jura), Saint Dizier, and many other places. 



85. Rhynchonella antidichotoma, Buv., sp. Sup., PI. VIII, figs. 19 — 21. 



Terebratula antidichotoma, Buvignier. Mem. de la Soc. Philom. de Verdun, 2, 



p. 13, pi. v, fig. 7, 1843. 

 Rhynchonella — D'Orb. Pal. Franc., Terr. Cretaces, p. 31, pi. 500 d, 



figs. 1—4, 1847. 



Spec. Char. Transversely oval. Ventral valve slightly convex, and flattened to about 

 half its length. Sinus broad, occupying rather more than one third of the anterior half of 

 the valve. Posterior half of the shell tapering on each side to a pointed and slightly 

 incurved beak. Foramen oval, surrounded and separated from the hinge-line by a 

 deltidium ; beak-ridges very sharply defined, leaving a rather wide flattened space between 

 them and the hinge-line. Dorsal valve much more convex and deep than the opposite 

 one ; fold broad, occupying rather more than a third of the posterior half of the valve. 

 Half or more than two thirds of the surface of each valve from the beak is marked by 

 numerous small rounded radiating ribs, fifty or fifty-five in number, which, after an 

 interruption in the growth of the shell, are succeeded by from twelve to seventeen large 

 projecting angular ones, of which from four to six compose the mesial fold or sinus. 

 The surface of the valves is also crossed by numerous concentric lines of growth. The 

 mesial fold and sinus is also, in some specimens, twisted or shifted from the centre to one 

 of the lateral portions of the valve so as to give the shell an unsymmetrical appearance. 

 Length 1 inch 2 lines, width 1 inch 5 lines, depth 10 lines. 



05s. This fine species varies a good deal in shape, some specimens being much more 

 convex than others. It has been well described and figured by both Buvignier and 

 d'Orbigny. 



Position and Locality. It occurs in the Lower Greensand at Upware and Potton, and 

 was found by M. Buvignier, in the " etage albien " of Grandpre (Ardennes), and by 

 M. d'Orbigny at Novion. 



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