PLEUROTOMARIA. 443 
Shell depressed, umbilicus deep and narrow. The spire is convex-depressed 
with a flattened apex. Whorls (seven) flat and sloping, and ornamented with 
oblique radial coste which are granulate at the points of intersection with the 
spiral system. 
The sinus-band forms a narrow, prominent ridge rather more than halfway 
down; owing to its prominence the spiral lines have not been well preserved, the 
general appearance being that of a narrow, winding cord. The body-whorl is 
relatively large, angular-compressed, and provided with a narrow, tuberculated 
carina at the periphery; base very convex and ornamented with a system of 
flexuous radial coste, which spring from the margin of the small but deep 
umbilicus. Aperture oval-depressed and oblique. 
Relations and Distribution.—Pl. plicopunctata differs from Pl. granulata in 
being more depressed, in its narrow but deep umbilicus, and especially in the 
conspicuous radial ornamentation of the base. In both there is a tendency to 
develop a tuberculated basal carina in the lower whorls of the spire, which adds 
materially to the beauty of the shell. 
It is mainly a fossil of the Parkinsoni-zone, beg especially abundant at 
Burton Bradstock, Vitney Cross, &c., also in the Parkinsoni-zone of Bradford 
Abbas, Stoford, &. There is considerable variety, with a tendency on the one 
hand to pass into Pl. Palemon, and on the other into Pl. trapeza. 
384. PinuroTomaria Patmmon, d’Orbigny, 1850. Plate XL, figs. 3a, 3b, 3c. 
1850. Prevroromarts PaLemon, d’Orbigny. Prod., i, p. 267. 
1854. — — — Terr. Jur., vol. ii, p. 468, pl. 
ceelxxx, figs. 7—11. 
1873. — PatzMon, d’Orbigny. Tawney, Dundry Gasteropoda, 
p. 48 (40). 
Syn. _ GRANULATA, vars. LENTIFORMIS and LZvieaTa, Deslong- 
champs. Vol. cit., p. 101, pl. xvi, figs. 4 and 5. 
Bibliography, §c.—It is pretty clear that Tawney, in quoting this species, was 
disposed to include both Pl. plicopunctata and Pl. Palemon under the latter 
designation. Undoubtedly they are near relatives. 
Description : 
Height : g ; : . I38>mm: 
Basal diameter ‘ 3 : . 309 mm. 
Spiral angle . ; . 142°. 
The sunken spire, fineness of the lines, and the absence of coarse radial 
ornamentation in the base, are the principal features which separate Pl. Palemon 
from the preceding species. It is essentially a fossil of the Parkinsoni-zone, and 
58 
