Vol. 68.] LOWEE CARBONIFEKOTJS GASTEROPODA. 307 



Pamily LoxonematidaB Koken. ' 

 MiOROPTrcHis, gen. nov. 



Diagnosis. — Shell elongated, conical. Whorls numerous, in- 

 creasing gradually, adpressed at the suture, flattened, convex at 

 the periphery. Earlier whorls ornamented by ribs nearly parallel 

 to the axis of the shell, later whorls devoid of ribs. A flat band 

 is situated on the widest part of the anterior whorls. Aperture 

 unknown. 



Genotype. — Microptycliis lurigJiti^ sp. nov. 



Remarks and resemblances. — The lines of growth are 

 imperfectly seen : apparently they are not so strongly sigmoidal as 

 in Loxonema Phill.^ sensu stricto, but more nearly resemble those 

 of Stylonema Pernor.^ They, as well as the ribs, seem to pass 

 over the band without break, therefore the latter cannot indicate 

 a slit in the outer lip. This genus is further distinguished from 

 Loxonema by the possession of this band, and also of ribs on the 

 earlier whorls. The more flattened form of the spire as well as the 

 ribs separate it from Ehabdostropha Donald.^ From Zygopleura 

 Koken * it differs in having a band and the whorls adpressed at 

 the suture. The latter feature also distinguishes it from Eustylus 

 Kittl.^ In general character it bears most resemblance to Ano- 

 ptychia Koken,® but that genus has the whorls subimbricated 

 and not adpressed at the sutures. 



Eange. — At present only known in the Lower Carboniferous. 



MiCROPTYCHIS WRIGHTI, Sp. UOV. (PI. XXX, figS. 6 d & 6 6.) 



Diagnosis. — Shell of medium size, composed of more than eleven 

 whorls. Ribs sharp and slightly curved on the upper five whorls, 

 becoming gradually less defined on the sixth and seventh ; band 

 discernible on the sixth, and becoming more distinct on the later 

 whorls. 



Remarks and resemblances. — So far I have only met 

 with one specimen of this species, which is in the collection of 

 Mr. Joseph Wright, Belfast. This is, therefore, the holotype. It 

 is quite distinct from any other described British species, but is 

 probably allied to Loxonema semicostatum,'' the first species described 

 by De Xoninck in his group Costata, which has ribs only on the 

 upper part of the spire ; it is, however, less slender, the whorls are 

 not so convex at the periphery, and the base is more produced. 

 L. murchisonianum De Kon.^ also possesses a band, but it is 



1 Q. J. G. S. vol. Ixv (1909) p. 212 & pi. x, figs. 1 a-\ b. 

 ^ ' Systeme Silurien Centre de la Bobeme ' pt. i, vol. iv, Gasteropodes, tome ii 

 (1907) p. 325. 



3 Q. J. G. S. vol. Ixi (1905) p. 565. 



4 Neues Jahrb. vol. ii (1892) p. 30. 



° Annalen dea k. k. Naturhist. Hofmuseums, vol. ix (1894) p. 192. 

 ^ Neues Jahrb. vol. ii (1892) p. 32. 



"^ ' Faune du Calcaire Carbonifere de la Belgique ' pt. iii, Ann. Mus. Roy 

 Hist. Nat. Belg. vol. vi (1881) p. 51 & pi. iv, figs. 8-9. 

 « Ibid. p. 60 & pi. vi, figs. 2, 33. 



