L. RICHARDSON AND J. W. TUTCHER : PTEROMYA CROWCOMBEIA ^ 
of preservation, but we consider it desirable to draw attention to the 
fact, and tentatively distinguish it as a variety — var. langportensis. 
Tate refers to a specimen from the White Lias of Somerset in the 
Bath Museum, named Pteromya crowcombeia by the author of the 
species else," he continues, " I should not have assigned our [Yorkshire] 
specimen to it."* Tate's doubts were quite justified, for whereas the 
valves of Pteromya crowcombeia from the Pteria-coutorta-^eds are 
dissimilar, those of the shells from the White Lias are similar, as is the 
case with the species from the Pleiiromya-l^eds. 
The specimen from Yorkshire figured by Tate is a small example 
of Pleuromya tatei. Associated with it, he states, are larger forms, 
which he suggests may be adult specimens. He draws attention to 
their close resemblance to Ceromya infra-liassica Peters, but our 
specimens do not agree with Peters' figure. | Possibly Tate's forms 
are our variety altior. 
volsellaJ hillana (j. sowerby). 
Plate IX., fig. L 
1818. Mineral Conckology, Vol. III., p. 19. plate 212, fig. 2. 
Remarks. — Sowerby's type came from " Pickeridge Hill, near 
Roundsford Park, Taunton." We figure a particularly fine specimen 
from the Pleuromya-'Beds, of the same locality. 
As will be seen on reference to the figures of Volsella Icevis (J. 
Sowerby) {Min. Conch., plate 212, fig. 2), and of this species (plate 
IX., fig. 5 of this paper), the latter is usually twice as large as an 
average-sized specimen of the former, and the anterior margin is 
practically straight. 
Volsella hillana (J. Sowerby) is very closely related to, and prob- 
ably the same as, F. glabrata (Dunker). § 
* The Yorkshire Lias, p. 406. 
f Von Karl F. Peters Uber den Lias von Fiinikirchen (1863), 
tab. 1, figs. 1-3. 
I =Modiola. 
§ " Ueber die in dem Lias Halberstadt vorkommenden Ver- 
steinerungen," PalcBontographica, t. I., p. 39, tab. 1, fig. 17. 
