GASTEROPODA. 79 



PLEUROTOMARIA OBESA, Desl. Plate X, fig. 11. 



PLECROTOMAHIA OBESA, Deslmgchamps. 1848. Mem. Soc. Linn, de Normandie. 



vol. viii, p. 134, pi. 14, fig. 1. 

 D'Orb. 1850. Prod. Paleont., p. 302. 



P. Testa trochiformi, apice subacuto, anfractibus rotundatis, in media subdepressis, 

 transverse striatis ; striis frequentibtis obsoletis, eequalibus, sinu angustissimo, profundissimo, 

 fascia sinus strictissimd, vix a striis distinctd, longitrorsum tamen densissime striatd, in media 

 anfractuum sitd, ultimo anfractu ad basim angulato-convexo ; basi subconvexd concentrice 

 striatd, striis rarioribus obsoletissimis, hinc et inde evanescentibus, umbilico magno, pervio 

 (parietibus subplanis), ad marginem sulcato, sulco sat parvo, spiraliter ascendente, sutures 

 internee vicino, sed ab ea distinctissimo ; aperturd subquadratd. (Deslongchamps.) 



Shell trochiform, apex subacute ; whorls somewhat convex, slightly depressed in their 

 middle, and transversely striated ; the striae, which are equal, are frequently obsolete ; the 

 sinus is narrow and deep, the band very narrow, so as scarcely to be distinguished from 

 the striae ; but it is densely striated longitudinally, and situated in the middle of the whorls ; 

 the last whorl is convexly angulated at the lower margin ; the base is somewhat convex, 

 concentrically striated, the striae being frequently scarcely distinguishable ; the umbilicus 

 is large, pervious (the sides nearly flat), sulcated at its margin, and ascends the interior 

 spirally, near to the internal sutures, but distinct from them; the aperture is subquadrate. 



Locality. We have only procured two specimens, which do not fully exhibit the 

 minute features of this species, so carefully described by M. Deslongchamps. Both were 

 obtained from the planking of Minchinhampton Common. Great Oolite, Ranville. 

 (Desl} 



PLEUROTOMARIA CLATHRATA, Goldf. Plate X, figs. 6, 6a. 



? PLEUROTOMARIA CLATHRATA, GoMfuss. 1843. Petref, p. 74, t. 186, fig. 8. 

 D'Orb. 1850. Prod. Paleont., p. 356. 



P. Testa trochiformi subdepressd, apice acuto, anfractibus planis, (5,) cingillis lineisque 

 crebris clathratis ; basi convexo-pland tenuissime clathrata; umbilico minima aut nullo; 

 anfractibus superne obsolete tuberculatis ; fascia sinus marginali. 



Shell trochiform, somewhat depressed; apex acute; whorls (5) flattened, their sutures 

 well marked ; covered with very fine, regular, equal lines, both longitudinal and transverse ; 

 the base is flattened or slightly convex, with a very fine cancellated surface ; umbilicus 



