PSEUDALARTA. 189 



of the didaetyl Alarias, such as those of the trifida-group. The form of the 

 aperture is peculiar and suggestive of Potamides, as was justly observed by Hebert 

 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 Cerithiidse or 

 the Turritellidas is not quite clear. The existence of a sort of posterior canal is 

 in favour of the former view. 



118. Pseudalaria Etheridgii, Tawney, 1873. Plate XII, figs. 6 a, 6 b, 6 c, 7, 8. 



1873. Alabia Etueridgii, Tawney. Dundry Gasteropoda, p. 14, pi. i, fig. 7. 



Cf. also 



1812. Tubeitella unicaeinata, Desl. Mem. Soc. Linn. Norm., vol. vii, p. 151, 



pi. xi, fig. 68. 

 1844. Cebitiiium concavum, Munst. Goldf., Petrifacta, t. 173, fig. 10. 



Bibliography, Sfc. — A single specimen from " Yeovil," i. 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. Cerithium concavum, M., 

 from the " Unter-Oolithe " of Rabenstein, has considerable resemblance. More- 

 over, Miinster's species has crenulated carinae, which is the case with Pseudalaria 

 Etheridgii, though the fact was not noticed by Mr. Tawney. 



Description : 



Length . . . . .20 mm. 



Width . . . . .8 mm. 



Length of body -whorl to entire shell . . 37 : 100. 



Spiral angle .... 24°. 



Shell conical, sharp ; whorls about ten, angular, spirally 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 



