PSEUDOMELANIA. 
239 
smooth and flat with close sutures, which presently begin to gape widely, when a 
sharp bevilled edge or keel appears at each extremity of the whorls, which under- 
goes a considerable amount of constriction. The lower of these sharp keels is 
ornamented with a variable amount of tubercles, which are well developed on 
the body-whorl, where they constitute a handsome carina at the commencement 
of the sloping base. 
Relations and Distribution. — Although so different in appearance to the close- 
sutured, smooth, and unornamented Ps. procera, the connection between the two is 
by no means difficult to trace, whilst the affinities with the next described species 
are still closer. Strictly speaking it is probable that the differences are varietal 
rather than specific. 
Pseudomelania hicarinata is abundant in the concavus-bed at Bradford Abbas, 
whence specimens were obtained by Dr. Wright. A similar but rather narrower 
shell, with gaping sutures and tuberculated caringe, occurs in the opalinus -zone of 
Burton Bradstock, and possible also in the Dogger. Similar forms occur in the 
Gryphite grit of Stroud. 
175. Pseudomelania HETEROCYCLA {Eugene Deslongchamps),186S — 69. Plate XVIII, 
figs. 4 a, 4 &, 4 c (variety). 
1863-69. Chemxitzia heteeoctcla, 'Eugene I) eslong champs. Notes Paleontolo- 
giques, p. 91, pi. 
viii, fig. 7. 
Description : 
Narrow and long variety from the concavtis-hed, Bradford Abbas : 
Spiral angle 
. 12°. 
Height of whorl to width 
. 1 : 1-2. 
Length of well-grown specimen 
110 mm. 
Wide and short variety from Coker : 
Spiral angle 
1— ‘ 
00 
o 
Height of whorl to width 
. 1 : 1-4. 
Length 
. 60 — 70 mm. 
The Coker fossil resembles the figure in the 
“ Notes paleontologiques ” more 
than the common form from Bradford Abbas. 
The following is the author’s 
description : “ Shell slender, with a sharp spiral angle (his figure shows an angle 
of 20°), whorls numerous, the number varying with the age ; smooth when young, 
but showing later on a keel near the suture, which ends in becoming a range of 
nodosities slightly marked, but more and more pronounced according as the shell 
advances in age.” 
