246 
PROCEEDINGS COTTESWOLD CLUB 
1920 
on the lateral area, but almost straight on the peripheral area. 
Siphuncle nearly central, or a little nearer the dorsal than the 
ventral area. Test not very thin, with irregularly-placed 
obscure folds, which follow the direction of the growth-lines, 
and are plainly visible on internal casts ; its surface covered 
with rather coarse growth-lines, which, rising from the umbilical 
suture, pass straight across the umbilical zone as far as the 
umbilical margin, whence they pass in a backward direction 
across the lateral area, making a very shallow sinus at about 
the middle of this area, as far as the peripheral margin, where 
they are deflected still farther backward so as to form on the 
periphery a rather deep and broad sinus corresponding to the 
hyponomic sinus of the apertural-margin ; the test on the 
peripheral area apparently also with fine obscure longitudinal 
lines. 
Measurements. 
Diameter 
about 99 mm 
Height of outer whorl 
5 i „ 
Thickness of outer whorl . . 
68 „ 
Width of umbilicus 
17 „ 
Height of outer whorl above 
preceding whorl 
42 „ 
Height of umbilical wall at 
greatest diameter 
about 19 „ 
Width of periphery at greatest 
diameter 
about 54 „ 
Remarks . — This species is easily distinguished by the 
quadrate section of its whorls, its rather broad, flattened 
periphery, and the direction of its growth-lines. The measure- 
ments given above are taken from a specimen which has been 
submitted to me by Mr. Richardson. There are also two 
examples in the British Museum collection, bearing the 
registered Nos. 19518/ and 19518m ; of these the latter is 
88 mm. and the former 65 mm. in diameter. 
Affinities and Differences . — This species bears some re- 
semblance to d’Orbigny’s, the figure given by d’Orbigny 1 of 
1 Pal. Franf. Terr, Jurass., tom. i. (1842), pi. xxviii. See also A. H. Foord, Cal. Foss. 
Ceph. Brit. Mus., pt. ii. (1891), p. 219. 
