SPIRIFERA. 65 



Sp. mesoloba, Phillips, has been placed by Mr. Morris among the synonyms of Sp. 

 glabra (' Catalogue/ p. 152) ; but the inspection of the original Gilbertsonian specimen in 

 the British Museum has convinced both Professor de Koninck and myself that the shell in 

 question will require to be considered as a variety of Martin's 8p. lineata, in which a 

 small mesial elevation is somewhat unusually developed, but exaggerated in the original 

 representation, of which fig. 10 of my PI. XI is a reproduction. 



I will only further remark that since the majority of authors seem inclined to maintain 

 both Sjj. lineata and S. elliplka, I have described them separately, but as varieties of a 

 single species, and must leave for future observers to determine whether or not this is to 

 be taken as a correct interpretation. 



The specific claims of Martinia stringocephaloides are very uncertain, notwithstanding 

 the lengthened description given by Professor M'Coy, at p. 141 of his ' Synopsis.' In 

 PI. XII, fig. 15, will be seen a reproduction of the author's original illustration, the 

 specimen from Lisnapaste being no longer to be found in Mr. Griffith's collection. 

 Pig. 16 is another example from Old Leighlin, in the Royal Dublin Society's Museum, 

 and stated to have been so labelled by the author himself. In Professor Phillips's 

 opinion, as well as in my own, these two shells bear so nnich external resemblance to 

 some 8. lineata that, until better evidence to the contrary arises, I have considered that 

 it will be preferable to leave it with the last-named species, as it is always desirable to 

 burden the nomenclature as little as possible. Professor M'Coy gives us the following 

 specific character : " Suborbicular, gibbous ; dorsal valve (our ventral one) produced in a 

 lengthened acute beak ; cardinal area narrow, acute, angular ; no mesial fold ; surface 

 marked with regular concentric lines." The only objections that could be adduced against 

 our interpretation is, that no radiating lines are mentioned, and that the beak of the 

 larger valve is more produced or lengthened than is usually the casein Martin's shell; 

 but this character is far from being constant, as seen by fig. 16. The radiating lines in 

 certain examples of Sp. lineata are likewise so faintly marked and so minute that they 

 may have become obliterated in the only two specimens that appear to have been found. 

 Professor M'Coy states, moreover, that " this remarkable shell seems to conduct to the 

 Pentamerce by means of Stringocephalus ;' but I cannot perceive the gradation, for the 

 shell in question possesses the spirals of a Spirifer, as represented by the author in his 

 woodcuts (figs. 24 and 25j while Fentamerus and Stringocephalus have an entirely different 

 internal arrangement ; he would have been nearer the mark had he mentioned that by its 

 external shape S. stringocephaloides conducted us to Athjris. The concentric lines or 

 ridges in Professor M'Coy's species are also exactly similar to those observable in 

 S. lineata. 



Loc. Sp. lineata and its variety, S. imbricata, are among the most abundant of 

 carboniferous limestone fossils. Martin found it at Castleton, Hope, Dovedale, and in 

 other localities of the main carboniferous limestone of Derbyshire, in the Black Rock, 

 Clifton, Bolland, and Settle, Kirkby Lonsdale, Crooklands, and the lower carboniferous 



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