SPIRIFERA. 47 



Obs. Sowerby's description and illustration does not convey a complete idea of all 

 the peculiarities of this interesting species. His figure represents only one of its numerous 

 variations, as will be better understood by a glance at our plate than by any lengthened 

 description. In it we have been able to illustrate those connecting shapes which unite 

 and explain the great differences observable between such specimens as figs. 1, 15, and 16. 

 Sp. distans is easily distinguishable from Sp. cuspidata, to which at times it bears some 

 resemblance by the shape of its fold and sinus. In Martin's shell the fold is regularly 

 convex, the sinus concave, without any ribs, while in Sowerby's species the fold is hardly 

 produced above the level of the lateral portions of the shell, with a central longitudinal 

 rib. The sinus is likewise more or less obscurely ribbed, with a mesial one of larger 

 dimensions. The hinge-line is also much longer in proportion than in Sp. cuspidata, the 

 fissure being likewise more narrow. 



Loc. Sowerby's specimen is stated to have been obtained near Dublin. Mr. Kelly 

 mentions Bundoran, Malahide, and Millecent as Irish localities. Professor Phillips found 

 it at Bolland. I am not acquainted with any Scottish examples. 



Spirifera bicarinata, M ( Coy} Plate VIII, fig. 18. 



Spibjfera bicarinata, M'Coy. Synopsis of the Carboniferous Fossils of Ireland, 



p. 129, pi. xxii, fig. 10. 



" Spec. Char. Rhomboidal, width more than twice the length, very gibbous ; sides 

 cylindrical ; mesial fold wide, smooth, concave on both valves, bounded on both valves by 

 two large, rounded, entire ribs on each side ; cardinal area with parallel sides, very wide 

 and hollow. This curious species is easily recognised by the mesial fold being concave, 

 and bounded by large keels on both valves. 



" Length 8 lines, width 1 inch 6 lines." 



Loc. According to Mr. Kelly, Millecent (Ireland). 



1 As the original example is no longer to be found in Dr. Griffith's collection, it would be hardly safe 

 to express an opinion on a species of which the author was able to illustrate but a very unsatisfactory and 

 insufficient fragment ; I therefore simply reproduce the original description and illustration. 



