PSEUDALARIA. 189 
of the didactyl Alarias, such as those of the trifida-group. The form of the 
aperture is peculiar and suggestive of Potamides, as was justly observed by Hébert 
and Deslongchamps. But in the modern Potamides there really is a canal, whilst 
in Pseudalaria there is little more than the semblance of one. Bearing in mind 
that both M. Cossmann and the late Mr. Tawney have borne testimony to the 
resemblance of these shells to Alaria, the name selected for the genus is not 
altogether inappropriate. Whether it should be placed under the Cerithiide or 
the Turritellide is not quite clear. The existence of a sort of posterior canal is 
in favour of the former view. 
118. PseupaLarta Erueripen, Tawney, 1873. Plate XII, figs. 6 a, 6 b, 6 ¢, 7, 8. 
1873. Anarta Eruertpeit, Tawney. Dundry Gasteropoda, p. 14, pl. i, fig. 7. 
Ct. also 
1842. Turrirerta unicartata, Desl. Meém. Soe. Linn. Norm., vol. vii, p. 151, 
pl. xi, fig. 68. 
1844. CrritHtum concavum, Minst. Goldf., Petrifacta, t. 173, fig. 16. 
Bibliography, §c.—A single specimen from “ Yeovil,” 7. e. from the Inferior 
Oolite of Bradford Abbas, was all the material available for Mr. Tawney, who was 
evidently unaware of the true nature of the aperture. Cerithiwm concavum, M., 
from the “ Unter-Oolithe ” of Rabenstein, has considerable resemblance. More- 
over, Miinster’s species has crenulated carine, which is the case with Pseudalaria 
Etheridgii, though the fact was not noticed by Mr. Tawney. 
Description : 
Length ; : : ‘ . 20 mm. 
Width : 5 . 8mm. 
Length of body- catioelst to entire shell : <, on 2100: 
Spiral angle é : 24°. 
Shell conical, sharp; whorls about ten, aia gala apirally striated, and 
provided with a very large keel, which is nearly median, sharp, and crenulate. 
A rudimentary second keel is partly exposed in the penult. Just below the 
suture in each whorl is a beaded band. 
The body-whorl is rather more than one-third the total height, and bicarinate, 
the anterior carina being quite equal to the other as it approaches the outer lip. 
Base flattish, and marked with spiral lines of considerable prominence. Aperture 
quadrate, outer lip sinuous and effuse, base very square, forming at its junction 
with the extremity of the columella an angular recess in imitation of a canal. 
There is also a short posterior canal. In section the earlier whorls are very 
similar to those of keeled Alarix, having about the same spiral angle, but in the 
