238 CATALOGUE OF THE FOSSILS OF THE PERMIAN SYSTEM 
Crass. GASTEROPODA, Cuvier. 
OrpER. PECTINIBRANCHIATA, Cuvier. 
Famity. [anrurnipg, Gray. 
8. PLEUROTOMARIA, Defrance. 
1. P. penza, d Vernewil. 
Pleurotomaria penea, d’Vern., Geol. Russ. ii., p. 336, pl. 
XK to cau: 
In Magnesian-limestone; rare. Dalton-le-Dale. 
This species is somewhat conical, with a short spire and about . 
four whorls, very much flattened above and slightly convex be- 
low. We have seen only two specimens of this species, which 
were not very well preserved, but as far as they could be com- 
pared they agreed with the P. penea of Russia. 
2. P. nopunosa, King. 
Pleurotomaria nodulosa, King, Geol. Russ. i., p. 225. 
In Magnesian-limestone; not common. Humbleton, Tun- 
stall, Garmonsway, near Coxhoe Hall. 
This species is easily distinguished from all others found in the 
limestone by its beautifully decussated surface, and by having 
one row of distinct wavy nodules round the suture, and another 
round the slit in full-grown specimens. In young specimens the 
nodules are absent. It is the largest species found in the Mag- 
nesian-limestone. We possess one specimen more than an inch 
in length and width. 
3. P, SEDGWICKII, 2. s. 
Pleurotomaria carinata, Geol. Russ. 1., p. 225 ; not Sow. nor 
Phill. 
Shell rather conical, small; spire, elevated ; whorls, 6 or 7, 
slightly keeled, flattened above, slightly convex beneath ; 
suture not deep, rather below the keel of the previous whorl ; 
surface with obsolete lines of growth ; pillar-lip straight, 
slightly reflexed, forming a small umbilicus, sub-angulated 
