﻿RHYNCHONELLA. 



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forms, externally almost undistinguishable, have been found by him to possess animals so 

 different in their anatomical details that they could not, in his opinion, be confounded 

 under the same specific denomination ; and it has been shown, by other similar investigations, 

 that shells presenting a wide range of external modifications of detail possessed an animal 

 exactly similar. This demonstrates the almost impossibility of very often determining 

 among the extinct forms what in reality belongs to the same species ; and our appreciations 

 must therefore be always more or less uncertain, however much zeal we may display in 

 our attempt to dive into the veiled secrets of nature. 



Professor M'Coy was mistaken while stating, at p. 151 of his ' Synopsis of the Carbo- 

 niferous Fossils of Ireland,' that the internal structure of R. acuminata was similar to 

 that of T. hastata, the one being a Rhynchonella, the other a Terebratula ; but his imper- 

 fect woodcut representation (fig. 32 of the ' Synopsis') would denote that the Professor 

 had observed the two small curved supports of the oral arms in Rhynchonella acuminata. 

 In PI. XX, fig. 6, the reader will find a more complete representation of the interior of the 

 dorsal valve, and the two woodcuts given above show the shape of the muscular and 

 vascular impressions. 



Loc. R. acuminata and its varieties abound in the Carboniferous limestone of many 

 English and Irish localities, but no well authenticated Scottish examples have hitherto 

 come under my observation. Martin mentions Bakewell and Buxton, in Derbyshire. It 

 is very common about Clitheroe and Bolland, in Lancashire, and at Park Hill, Longnor, 

 Derbyshire ; at Settle and Malham Moor, in Yorkshire ; in the Isle of Man, &c. 



In Ireland, Mr. Kelly mentions Mullaghfin, Millecent, Little Island. 



On the Continent R. acuminata was found at Vise, in Belgium, by Professor L. de 

 Koninck ; at Hausdorf, by M. De Semenow ; and at Cosatchi-Datchi (Oural), by M. de 

 Verneuil and Count Keyserling, &c. 



Rhynchonella pugnus, Martin (sp.). PL XXII, figs. 1 — 15. 



Conchyli oltthus anomites pugnus, Martin. Petrificata Derbiensia, tab. xxii, figs. 4, 5, 



1809. 



Terebratula pugnus, Sowerby. Min. Con., tab. ccccxxv, figs. 1 — 6, 1825. 



— — Phillips. Geology of Yorkshire, vol. ii, p. 222, pi. xii, figs. 17 (but 



fig. 16 should also be included), 1836. 



— sulcirostris, Phillips (?). Geology of Yorkshire, vol. ii, p. 222, pi. xii, figs. 



31, 32, 1836. 



Atrypa pugnus, M'Coy. Synopsis of the Characters of the Carboniferous Fossils of Ireland, 

 p. 156, 1844. 



— laticliva, M'Coy (?). Ibid., p. 154, pi. xxii, fig. 16. 

 Terebratula pugnus, De Verneuil and Keyserling. Geology of Russia, vol. ii, p. 78, pi. 

 x, fig. 1, 1845. 



Hemithyris acuminata, var. pugnus, M'Coy. British Palaeozoic Fossils, p. 338, 1852. 



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