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 bicarinata 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 carinz, occurs in the opalinus-zone of 
Burton Bradstock, and possible also in the Dogger. Similar forms occur in the 
Gryphite erit of Stroud. 
175. PsrvupoMELANIA HETEROCYCLA (Hugéne Deslongchamps), 1863—69. Plate XVIII, 
figs. 4a, 4b, 4c (variety). 
1863-69. CHEMNITZIA HETEROCYCLA, Eugine Deslongchamps. Notes Paléontolo- 
giques, p. 91, pl. 
viii, fig. 7. 
Description : 
Narrow and long variety from the concavus-bed, Bradford Abbas : 
Spiral angle : : sage 
Height of whorl to width : : oe altsey tee 
Length of well-grown specimen : . 110mm. 
Wide and short variety from Coker : 
Spiral angle : ' Slice: 
Height of whorl to width 5 ; S aics 
Length . 60—70 mm. 
The Coker fossil Peeled the Aunt in the ‘ eNotes malconteloeiques ? more 
than the common form from Bradford Abbas. The following is the author’s 
description: ‘‘ Shell slender, with a sharp spiral angle (his fizure 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 peeuely marked, but more and more pronounced according as the shell 
advances in age.” 
