64 BRITISH OOLITIC AND LIASIC BRACHIOPODA. 



61. Terebratella hemispheric^, Soio. Plate XIII, figs. 17, 18. 



Terebratula iiemispHjErica, Sow. 1829. Min. Con., vol. vi, p, 69, tab. 536, fig. 1. 



— . — Deslong champs. 1837. Soc. Linn, de Normandie. 



— — Morris. 1843. Catalogue, p. 133. 



— — Bronn. 1849. Index Palseont, p. 1238. 

 Terebratella — TfOrb. 1849. Prodrome, vol. i, p. 316. 



Diagnosis. Shell inequivalved, hemispherical • beak produced, recurved, truncated by 

 a large oval foramen placed more under than above the apex of the beak, encircled by a 

 portion of the extremity of the beak, cardinal area, disunited triangular deltidium, and 

 summit of the umbo of smaller valve, which is commonly quite, or nearly flat ; hinge line 

 slightly arched ; structure punctuated ; surface of valves ornamented by numerous small 

 longitudinal elevated striae often bifurcating. Loop said to be doubly attached to crura 

 and to central longitudinal septum. Length 4, width 3^, depth 2 lines. 



Obs. Von Buch is in error when stating in his valuable Monograph of Terebratula^ 

 that this species is only a synonym of T. gracilis, a cretaceous shell easily distinguishable 

 from T. hemisplicerica ; in shape and characters it is a well-defined species, varying less 

 than most oolitic shells ; however, although its great and common character is to have an 

 almost flat imperforated valve, still in some specimens, and especially in many from 

 Normandy, this valve is more or less convex. 



Notwithstanding my own and M. Deslongchamps' endeavours we have not been able 

 to clear a specimen, so as to see the interior loop in a satisfactory manner, and therefore 

 have placed it in the present genus, more on M. D'Orbigny's authority than our own, as 

 we consider a knowledge of the form and position of the process absolutely necessary to be 

 able to state positively to what genus or subgenus of the great family of Terebratulae each 

 species belongs. 



Terebratella hemispluzrica is found in the Great Oolite of Hampton Cliff, near Bath, 

 and at Luc and Langrune, near Caen, in which last locality M. Deslongchamps obtained 

 some specimens larger than any hitherto found in England, where it does not seem to 

 exceed the dimensions above given. Fig. 17 natural size; fig. 18 are considerably 

 enlarged illustrations. 



