BRITISH PERMIAN BRACHIOPODA. 



characters of any of the Terebratulid^: ; for T. pentahedra appears to possess spirals, 

 and is consequently an Athyris ; while S. pisum, M'Coy = T seminula} Phillips, and 

 S. rhomboidea, Phillips, are Rhynchonell^e. 



In 1855, Professor M'Coy describes his genus thus : " Gen. Char. Ovate; a large oval 

 perforation on the beak of the receiving valve (ventral or dental one), separated from the 

 hinge-line by a portion of the valve, but apparently without deltidium ; dental lamellae 

 strongly developed in beak of receiving valve, slightly diverging entering valve (dorsal, 

 Owen), with a faint trace of mesial septum, and two cardinal teeth, from whence a small 

 loop, with a very short recurved portion, arises ; substance of the shell punctuated, usually 



without plaits Lately, Professor King has given much excellent information on 



the genus, in his volume on the ' Permian Fossils of England,' under the name of Epithgris 

 of Phillips, and pointed out the valuable and easily ascertained character of the strong 

 dental lamellse in the beak, bordering the foramen. From the observations in the middle 

 of p. 54 of Phillips's ' Palaeozoic Fossils,' it is obvious, however, that Epithgris was 

 intended for the Oolitic Terebratula, congeneric with T. maxillata, having distinct 

 deltidium, &c. The dental lamella? leave slits in the beak of the casts, one on each side 

 of the foramen, which are very characteristic of the genus, and in some states of exfoliation 

 of the shell are likely to be confounded with the edges of the deltidium ; indeed, the 

 appearance thus produced in many specimens is so puzzling, that I prefer leaving the 

 existence or non-existence of a deltidium an open question, the genus being well distin- 

 guished meanwhile from the more recent Terebratula by the rostrum being separate from 

 the extension of the dental lamellse, &c. This generic type seems confined to the Palaeozoic 

 rocks. Examples : T elongata, Schloth. ; T. jicus, M'Coy ; T. hastata, Sow. ; T juvenis, 

 Sow. ; T. sacculus, Martin ; T seminula, Phillips ; 2 T sufflata, Schloth. ; T. virgoides, 

 M'Coy." 



All these shells belong to the same generic type of Terebratulidcs ; but the question to 

 be determined is, whether they should be separated from Llhwyd's genus, and if so, 

 whether Professor M'Coy's denomination should be the one selected. For the sake of 

 comparison, I have tabulated the differences observable between Terebratula, Llhwyd, and 

 those shells which are considered by M'Coy and King to constitute a separate genus. 



1 Professor M'Coy seems to have entirely misunderstood Professor Phillips's T. seminula, as will be 

 found explained in my Monograph of Carboniferous species. 



2 The shell described as T. seminula (Phillips) by Professor M'Coy in 1855 is T. vesicularis, De 

 Koninck, and not T. seminula of Phillips, nor the one made use of in the * Synopsis.' 



