TEREBRATULA. 47 



Obs. As Sowerby remarks, when describing this species, it sometimes shows little or 

 no marks of that indentation from which the name is derived ; it is one of those species 

 which present some difficulties, not being as well characterised as we might wish, and 

 leading us, by gradual links, into Ter. punctata, with which it is generally associated. It 

 occurs in the middle Lias of Banbury, as stated by Mr. Sowerby ; it was found also at 

 Deddington by Mr. C. Faulkner, where it is associated with Ter. resupinata. It is common 

 at Farington, Gurney, &c. M. D'Orbigny erroneously considers this species as a synonym 

 of Ter. digona, {vide ' Prodrome,' p. 315,) from which it is perfectly distinct, and belongs to 

 the Lias, and not to the Bath Oolite, as stated by that author. Its loop is short, extending 

 only to less than half the length of the shell, while in Digona it nearly reaches the frontal 

 margin of the shell. This species is also found on the Continent, but does not appear to 

 be known to the Palaeontologists there. Figs. 25, 26, from the Collection of Mr. Walton. 



44. Terebratula insignts, Schubler. Plate XIII, fig. 1. 



Terebratula insignis, Schubler. Zieten, 1832. Die Verst. Wurtembergs, pi. xl, fig. 1. 



— — D'Orb. 1849. Prodrome, vol. i, p. 376. 



— — Quenstedt. 1843. Dos Flozgebirge Wurtembergs, p. 484. 



Diagnosis. Shell inequivalved, more or less oval, longer than wide ; valves convex, 

 deepest towards the posterior portion ; beak produced, slightly recurved, and obliquely trun- 

 cated by a moderately-sized foramen, separated from the umbo by a rather long deltidium 

 in one piece ; lateral ridges indistinct ; in smaller valve a well-defined mesial fold is seen to 

 extend to the front, with lateral depressions ; larger valve regularly convex, no deep sinus 

 corresponding to the elevation in its smaller valve ; surface smooth, punctuated ; loop 

 short, simply attached to crura, and extending to less than half the length of valve. 

 Length of our British specimen 20, breadth 15, depth 11 lines. 



Obs. This remarkable Oolitic species has not before this been noticed in England ; 

 it occurs in the Oxford Clay of St. Ives, and in the Coralline Oolite of Malton. It 

 seems little known even to Continental Palaeontologists. Von Buck 1 erroneously considers 

 it a synonym of T. perovalis, and Dr. Bronn 2 the same as Ter. biplicata, likewise a 

 mistake : it is perfectly distinct from both by its general appearance, and especially by its 

 deltidium formed of one piece instead of two, which is the case with both T. perovalis and 

 biplicata. This species was well figured by Zieten in 1832, and correctly noticed by 

 M. D'Orbigny in his ' Prodrome ;' he places it both in the Oxford Clay and Coralline Oolite. 



1 Mem. Soc. Geol. de France, vol. iii, l" e Serie, 1838. 



2 Index Palseontologicus, vol. ii, p. 1239. Dr. Bronn's synonyms of Ter. biplicata are far from being 

 correct, and it is evident that Sowerby's species is little known. 



