BRITISH SILURIAN BRACHIOPODA. 158 



and transversely striated. Valves articulated by two slender curving teeth, proceeding from 

 a broad curving hinge-plate in the ventral valve, which fit into corresponding sockets in the 

 dorsal valve. Crura rising from near the dorsal beak, and curving into the ventral cavity, 

 and thence recurved towards the dorsal side, and probably uniting, as shown in fig. 4, 

 p. 167 (of his work). Structure fibrous and apparently very minutely punctate." 



From the above and what follows it is evident that Prof. Hall has not seen the short 

 Terebratula-shaped loop represented in his restored figure No. 4, for he says in his 

 description "and probably uniting, as shown in fig. 4," and in the explanation of his 

 figure 4 he adds, " the additional features of the loop represented in this fig. 4 have not 

 yet been satisfactorily determined." 



In order, if possible, to ascertain the internal characters of this species, I asked the 

 Rev. Norman Glass to develop the interior of some ST^ecimens of Bk. cuneata ; and, having 

 experimented on a number of them from the Wenlock Limestone of Benthall Edge, he 

 found that all of them showed only two curved lamellae rising from the hinge-plate and 

 not attaining a third of the length of the valve (as in Rhynchonella) ; and in no instance 

 did Mr. Glass see any indication of a loop. 



I would, therefore, leave Dalman's species with Bhynchonella until, on positive 

 evidence, it can be shown to be generically separable. The beak in Hh. cuneata is more 

 or less elongated and attenuate ; its extremity is truncated by a circular foramen more 

 or less separated from the hinge-line by a deltidium. 



In the interior of the dorsal valve of a specimen of JRJi. cuneata from the Upper 

 Llandovery of Speakes Rough, in Shropshire, or rather in an impression of the interior 

 taken in gutta-percha from an internal cast (Sup., PI. X, fig. 10 a), we find along the 

 bottom of the valve, from under the hinge-plate to two thirds of its length, a narrow 

 mesial septum. The cardinal process is small ; and on either side the hinge-plate presents 

 two slightly concave pear-shaped plates. 



Rh. cuneata occurs plentifully in the Upper-Silurian rocks of England and Sweden, 

 and in the Upper Llandovery of the neighbourhood of Minsterley. It has also been found 

 by Mrs. R. Gray in a brown ferruginous gritty sandstone of Middle Llandovery age at 

 Newlands, in the Girvan district of Ayrshire, also in the Lower Llandovery at Mullock 

 Hill, in the same county. 



According to Mr. Salter, it occurs likewise in a yellow sandstone at Lower 

 Tliraive, in Ayrshire, in a rock attributed by Prof. Lapworth to the Upper Caradoc. 

 Specimens also that cannot be satisfactorily distinguished from Bh. cuneata have been 

 founded by Mrs. R. Gray in the Upper Llandeilo of Craighead, Balcletchie, and 

 Ardmillan Brae, Ayrshire ; but this point will require further confirmation. 



Prom the above it appears that this species, with slight variations in shape, was 

 represented from the Caradoc (?) to the Wenlock or even the Ludlow period. 



