PSEUDOMELAXIA VITTATA. 77 



are sufficiently related amongst themselves to justify a group of their own. 

 They have elongated, pointed spires, growing to a considerable size, their aperture 

 oval, entire, regularly rounded in front, and terminating posteriorly in an angle. 



Genus PSEUDOMELANIA, Pictet and Campiche. 



Shell thick and not umbilicated, ornament usually confined to lines of growth, 

 columella thick. The principal shells placed here are divisible into two groups, 

 one with smooth, rounded whorls with only lines of growth [these are called 

 anoptychia by Koken], and the other with a spiral rib near the tip of the whorls, 

 at least in the adult [called hypsipleura by Koken]. 



The Pseudomelanias of the Cornbrash have been recorded under the old name 

 of Chemnitzia or even Melania. 



0. heddingtonensis (5, 0). C. scarburgensis'i (44). 



*G. simplex (40). *G. vittata (5, 6, 15, 21, 25, 28, 34, 40, 42, 44, 48). 



Of these heddingtonensis has never been recorded since. The only recognisable 

 difference between this species and P. vittata lying in the prominence or presence 

 of ornaments, imperfect ones might be registered under this name without both 

 species being present. P. scarburgensis has been recorded with a (?) only from 

 Appleby, and no such specimen has been seen in Mr. Cross' collection. P. simplex, 

 recorded by Sharp from Peterborough-Stilton district, is represented by two speci- 

 mens in Birmingham University, but they are worn casts as usual and show no 

 definite features. 



Pseudomelania vittata (Phillips). Plate VIII, figs. 1, 2. 



1835. Melania vittata, Phillips, Geol. Yorks., p. 116, pi. vii, fig. 15. 



1853. Chemnitzia vittata, <■/. Lycett, Suppl. G. O. Mollusca (Pal. Sue), p. 14, pi. xxxi, fig. 10. 



1875. — — Phillips, up. cit., 3rd edition, p. 257. 



1882. Hudleston, Geol. Mag. [2], vol. ix, p. 244, pi. vi, figs. 5, 5 a, 6. 



Tj/pe is constituted by Phillips' figure only. 



Description. — There are about ten to twelve whorls when adult; corresponding 

 projections lie in a straight line longitudinally. At the apex the surface is smooth 

 and conical, and shows only lines of growth with an undulating twist. These are 

 crossed by fine spiral fimbriated lines. At a diameter of 7 mm. the posterior front 

 begins to rise and the anterior outside edge becomes angular. The suture makes 

 an angle of 75° with the axis. The posterior border rises gradually till the anterior 

 edge becomes a sharp spiral and the rest slopes down backwards to the suture ; in 



