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BRITISH CARBONIFEROUS BRACHIOPODA. 



D. Rhynchonella (?) gregaria, M'Coy. PI. XV, figs. 27, 28. 



Atrypa gregaria, M'Coy. Synopsis of the Carboniferous Fossils of Ireland, p. 153, pi. 



xxii, fig. 18, 1844. (Not Atrypa gregaria, M'Coy, British Palaeozoic 

 Fossils, p. 435, tab. iii d, fig. 20, 1855). 



" Spec. Char. Trigonal ; beak of the dorsal valve {ventral, Owen) very large, produced, 

 incurved ; dorsal valve flattened ; sides abruptly rounded ; a very wide, but shallow, mesial 

 depression, slightly produced in front ; ventral valve {dorsal, Owen) an equilateral triangle ; 

 all the angles rounded very convex ; front margin raised to a broad sinus ; surface smooth." 

 "This curious species K very remarkable in form, wholly unlike any of the other Palaeozoic 

 species, approaching in size and shape to the Terebratula lineolata, Phil., of the Speeton 

 Clay ; it is the only true Atrypa I know of, resembling in this respect several of the 

 Terebratula of the more recent formations. Length seven lines, width six lines, depth 

 three lines and a half." (M'Coy, 1 Synopsis,' p. 153.) 



Obs. Of this shell I am acquainted with but the single ventral valve, that was kindly 

 lent to me by Sir R. Griffith, and which I found to agree with the same valve that is 

 figured by Professor M'Coy in his 'Synopsis;' but all my efforts to procure a bivalve 

 example or the dorsal valve have proved unsuccessful. On such insufficient material I 

 could not venture to describe the species, and have, therefore, reproduced that given by 

 Professor M'Coy in 1 844 ; for I cannot admit that the shell subsequently published as 

 Athyris gregaria in the work on ' British Palaeozoic Fossils ' by the same author, could 

 belong to the same species as that of the ' Synopsis/ 1 I am also uncertain as to its genus, 

 and although placed in PI. XV among the Athyrises with a point of doubt, I now prefer 

 to locate it provisionally among the Rhynchonella, on the simple authority of M'Coy's 

 figures, which bear more resemblance to a Rhynchonella than to an Athyris. In my plate I 

 have reproduced Professor M'Coy's three original figures, and have added a drawing of 

 the ventral valve that was kindly lent me by Sir R. Griffith. 



Mr. Kelly mentions that the species was derived from the Calcareous slate of Ballinglen, 

 Kilbride, and White River, in Ireland ; but the specimen lent me by Sir R. Griffith had 

 all the appearance of having been taken from the Carboniferous limestone. I am not 

 acquainted with any English or Scotch specimens. 



1 It belongs to Professor Hall's Athyris subtilita. 



