SPECIES OF CARBONIFEROTJS MTJECHISONIA. 567 



The body- whorl of the Scottish shell is too imperfect to show whether 

 there was an additional keel upon it. With regard to the remark- 

 able difference in size, it has been previously observed that many 

 Scottish fossils are dwarfed as compared with the same species from 

 other localities, and this appears to be especially the case with those 

 from Dairy. In a former paper I described a variety of M. turri- 

 culata, De Kon., from the shales of the Upper Limestone Series ^ 

 (Dairy), diifering as greatly in size from the type as the present 

 form does. In the absence of specimens of intermediate dimensions, 

 and considering that the Scottish shell is only about half the size of 

 the Belgian one, it seems advisable, in the meanwhile at any rate, 

 to let it constitute a distinct variety for which I should suggest the 

 name pulchella. 



This species bears a great resemblance to M. quadricarinata, 

 M'Coy, from which it may be distinguished by the higher position 

 of the angle, more oblique sutures, and also in its being of much 

 greater size than the specimens of M. quadricarmata from the 

 Scottish beds. It may, however, be an elongated variety of that 

 species, but this could only be proved by the comparison of a large 

 series of specimens which might show intermediate forms. 



Locality and Formation. Law Quarry, Dairy, in the shales of 

 the Lower Limestone Series. 



MuECHisoNiA (Htpeegonia.) conula, De Kon», var, convexa. (PI. 

 XVI. figs. 8, 9.) 



Murchisonia conula, L. G. de Koninck, 1843, * Precis elem. de 

 Geologic' par J.-J. d'Omalius d'Hailoy, p. 516. 



Murchisonia abhreviata, L. G. de Koninck, 1843, ' Descr. des 

 Anim. foss. du Terr. Carb. de la Belgique,' p. 415, pi. xxxviii. figs. 3 

 et6. 



Murchisonia angulata, L. G. de Koninck, 1843, ibidem, p. 412, 

 pi. xxxviii. fig. 8 (synonymis et tab. xl. fig. 8 exclusis) ; H. G. 

 Bronn, 1848, ' Index pal.' p. 747 ; A. d'Orbigny, 1850, ' Prodr. de 

 Paleont. stratigr.' p. 122 ; J". J. Bigsby, 1878, ' Thes. Devonico- 

 Carboniferus,' p. 325. 



Murchisonia conula, L. G. de Koninck, 1883, ' Faune du Calc. 

 Carb. de la Belgique,' vol. viii. pt. 4, p. 17, pi. xxxiv. figs. 9, 10. 



^Murchisonia quadricarinata, L. G. de Koninck, ibid. p. 20, 

 pi. xxxiv. figs. 17, 18. 



Shell elongated, turriculated, somewhat convex in outline. 

 Whorls from twelve to fifteen, very gradually increasing and but 

 slightly angular. Ornamentation consisting of four keels ; the keel 

 on the angle and that next below strong and almost equally pro- 

 minent, the uppermost and lowest keels much finer. The upper- 

 most keel divides the space above the angle almost equally in two ; 

 the lowest keel appears immediately above the suture. Base flat- 

 tened, having no additional keels, but having numerous fine spiral 

 lines. Sinus situated between the keel on the angle and the upper- 



^ ' Descr. of some New Species of Carb. Gasteropoda,' Quart. Journ. Geol. 

 Soc. vol. xlv. (1889) p. 622. 



