240 GASTEROPODA OF THE INFERIOR OOLITE. 
Relations and Distribution.—The most peculiar feature of Ps. heterocycla is a 
sort of reversed turriting which arises from the overlap of each whorl by its 
predecessor in the adult or carinated portion of the shell. It is this character, in 
conjunction with the slight constriction of the whorl, which serves to distinguish 
it from Ps. bicavinata. But the two forms run into each other very much, 
especially in the Bradford Abbas beds, so that they might be regarded as one 
species. In such cases, the older name, hetevocycla, would seem to have the pre- 
ference, although possibly there might be no overlap of the whorls. 
It is noteworthy that Eugéne Deslongchamp’s type comes from the so-called 
Sowerbyi-bed of the forest of Haye (Meurthe), and not from the ‘‘ Odlithe ferugi- 
neuse.”’ This shows it to be a fossil of the Lower Division, which is exactly what 
we find on this side the channel. The Coker-beds are in the Murchisonx-zone. 
The narrow form is extremely abundant in the concavus-bed at Bradford Abbas, 
and this same form occurs also in the Lower Trigonia grit of Leckhampton. 
176. PsEUDOMELANIA, species or variety. Plate XVIII, fig. 5. 
Description : 
Spiral angle : : does 
Height of whorl to width : : 5 ibe ilo2'5- 
Length R : . 85mm. 
This form approaches Ps. “peearinitas but has the whorls shorter, and the 
sutures do not gape so much. In the shortness of the whorl and wider spiral 
angle it more resembles the Coker variety of Ps. heterocycla. 'The nodosities 
are coarser than in either species. 
As a mere distinction this may be known as Pseudomelania “robusta.” A 
single specimen from the opalinus-zone (Moorei-beds), Coaley Peak. 
177. PsnupoMELANIA, species or variety. Plate XVIII, fig. 6. 
Description : 
Spiral angle é : cy PaLBE: 
Height of whorl to walls é ; pales alse 
Length : : ‘ : . 70 mm. 
This form differs from Ps. procera in the wider spiral angle and somewhat 
