24 BRITISH PERMIAN BRACHIOPODA. 



enabled me to offer a few additional illustrations, in which certain parts are perhaps more 

 completely expressed. Thus, fig. 25 shows the hinge and different shelly processes in a 

 very distinct manner, as well as do the detached valves, figs. 15 and 24 ; but the point on 

 which I should desire to direct more particular attention is to those defined and often 

 deeply indented impressions visible or either side of the septa (as seen in the casts, 

 figs. 11, 12, 13, 14, and 23), and which I am disposed to believe are in a great measure 

 due to the adductor (a) in the dorsal, and to the cardinal muscles (b) in the ventral valves. 

 Professor King does not appear to coincide in this interpretation ; but when I compare 

 these markings with those observable in the interior of Bhynchonella, I am naturally led 

 to conclude from their shape and position that they may be attributable to a similar 

 origin. 



Three species only have been discovered in British Permian localities, and they present 

 the same internal details, which appear to be simply more or less developed, according to 

 the dimensions and age of the individual. In the ventral valve the dental plates are 



from D'Orbigny having placed Camarophoria Schlotheimi, along with Rhynchonella Geinitziana, in the 

 same genus, it is evident the French author was neither acquainted with their internal character nor 

 dissimilarities. More merit is therefore due to M. De A 7 erneuil and to Count Keyserling for having placed 

 the two above-named shells in separate genera, and particularly to Professor King, who first described 

 their differences. 



Rh. Geinitziana was likewise found in Germany by Dr. Geinitz and Baron Schauroth ; and it was 

 while describing some examples of this last from Ropsen, near Gera (in the ' Annals of Nat. Hist.' for 

 March and April, 1856), Professor King announced for the first time that, in his opinion, the shell- 

 structure was regularly perforated as in Terebratula. So anomalous a condition in a genus and family 

 where all the species hitherto examined by Dr. Carpenter had proved to possess a fibrous non-perforated 

 texture, made me very desirous that the subject should be further investigated before the statements made by 

 Professor King should be admitted as an established fact. I therefore obtained, through the kind medium 

 of Count Keyserling and General Helmersen, the loan of those Russian individuals collected by Count 

 Keyserling near the river Oukhta, and which form part of the collection of the " Corps des Mines " of St. 

 Petersburgh. M. De Verneuil likewise kindly communicated his original specimen, and to which were 

 added others from German individuals, presented to me by Baron Schauroth and Professor King. These 

 I submitted to Dr. Carpenter, who, on the 17th of February, 1857, after a careful and minute micro- 

 scopical examination of shreds, removed in my presence from the exterior of the best preserved of the 

 Russian shells, declared that he could perceive no perforations in their outer layer, but that in the German 

 examples the inner surface was covered with minute pits, such as are seen on the outer surface of Poranbo- 

 nites ; but at that period Dr. Carpenter had not made any vertical sections through the entire thickness of 

 the shell. But as Professor King had observed numerous dots on the Russian and German specimens 

 which he considered to be due to perforations passing directly through the entire thickness of the shell, 

 the specimens and preparations made were shown by Dr. Carpenter to Professors Quekett and Salter, who 

 both entirely coincided in the opinion expressed on the 1 7th of February, viz., that the outer or first-formed 

 layer (in perfectly preserved specimens) was not perforated ; but also agreed that a considerable thickness 

 of the inner ones were perforated, and which last corresponded with the portion of the shell examined by 

 Professor King. Therefore, although it appears certain that a part of the thickness of the shell is traversed 

 by passages, there exists an external layer quite free from such, so that the shell-structure cannot be 

 considered exactly the same as in Terebratula. 



