1G BRITISH DEVONIAN BRACHIOPODA. 



a third of the length of the valve. To the inner extremities of the socket-ridsres are fixed 

 the spinal processes, with their extremities directed towards the lateral margins of the 

 shell. The spiral cones are united by a complicated system of lamellae, somewhat as in 

 A. peetinifera, A. Bogssii, &c. No defined septum is observable in this valve, but a rudi- 

 mentary mesial ridge divides the quadruple impressions of the adductor. In the ventral 

 valve the dental plates are tolerably developed, while the adductor leaves a small oval scar 

 towards the middle of the valve, and which scar is separated into two parts by a minute 

 mesial elevation, under and outside of which are seen the large impressions of the 

 divaricator muscle. Proportions variable ; the largest English specimen I have seen 

 measured — length 13, width 15, depth 8 lines. 



05s. This species is characteristic of the Upper Devonian strata of France, as well as 

 of other countries, but does not appear to be very common in Great Britain, if I may so 

 judge from the very scanty and imperfect material I have been able to assemble. 



In Devonshire a few adult but incomplete examples have been found by Mr. Pengelly 

 in shales at Mudstone Bay. Internal casts showing the muscular impressions have been 

 met with by Mr. M. Hall in brown grits of the Marwood and Pilton Upper Devonian (?) 

 series at Orchard quarry, Pilton, one mile north of Barnstaple, and large impressions of 

 the same shell were found by the same gentleman at Croyde Bay, seven miles west- 

 north-west of Barnstaple. 



A. concentrica has been met with at Hope's Nose, near Torquay, and in dark-gray slate 

 at Galmpton Creek, on the River Dart, but usually in a very fragmentary and contorted 

 condition ; and it has also been obtained from the Upper Devonian strata of South 

 Petherwin, in Cornwall. At page 130 of his 'Catalogue,' Professor Morris mentions that 

 the shell occurs in the Middle Devonian of Newton and Ogwell, in Devonshire ; but 

 from those places I have not seen specimens. 



On the Continent it is a common fossil at Ferques and Nehou, in France ; at Refrath 

 and Gladbach, in the Eifel; at Iliibigenstein, Tchudovo, &c. ; but I am not quite certain 

 whether it has been really discovered in America, notwithstanding that the Athyri* (Tere- 

 hratula) spiriferoides, Eaton, has been referred to A. concentrica (but with uncertainty), 

 by M. Dc Vcrncuil, Conrad ('Ann. Rep. New York,' pi. hi., 1832), and others. In 

 his 'Final Report, 4th District, New York,' p. 198, fig. 5, Professor Hall expresses a 

 similar opinion to that advocated by M. De Verneuil ; but subsequently, in the ' Report of 

 the Regents of the University,' p. 113, 1857, he observes that "this species (the Spin/era 

 spiriferoides) has generally been referred to the Terebratula (Spiriyera) concentrica of Bronn, 

 from which it differs in the straightness of its hinge and much less prominent beak. It 

 also presents other slight but constant differences of form, the broadest part being almost 

 always a little above the middle, while in T. concentrica it is generally a little below it (?). 

 The lamellae are likewise more distinctly imbricated in our shell than in Sp. concentrica. A 

 comparison of the European specimen with the American ones has shown the propriety of 

 separating them, and of adopting the name given by Eaton in ' Silliman's Journal,' 1831." 



