98 EEV. B. BOOG WATSON ON THE 



Shell. — Globosely conical, not thin, but waxily translucent, with 

 a thin polished yellow epidermis. Sculpture. There are many 

 oblique, fine, rather obsolete lines of growth. Spirals. There are 

 several irregular, unequally parted, rounded and rather obsolete 

 spiral threads, which are closer on the base. Colour. That of the 

 shell is a translucent white; it is covered with a very thin, most 

 persistent, hard, smooth, and horny epidermis. Spire somewhat 

 turreted. Apex eroded. Whorls 3 (remaining), convex, but a little 

 compressed towards the middle, round on the base, of very rapid 

 increase, the mouth being fully two thirds of the whole length. 

 Suture deep and irregular, but not canaliculated, except where 

 eroded. Mouth oval, bluntly pointed above, glossy within. Outer 

 lip thin and sharp, with a very regular curve, prominent on the 

 base, and a little patulous towards the point of the pillar, where 

 it is slightly, openly, and a little obliquely canaliculate. Pillar 

 rather short, hollowed above, bending over a little to the left and 

 terminating in a slight oblique tooth, which results from the slight 

 canaliculation in which the mouth terminates, and which, as in 

 Rissoina, is hollowed out of the point of the pillar. Inner lip 

 porcellanous white, slightly reverted, and very closely appressed ; 

 a very thin glassy layer across the body unites the lips. Um- 

 bilicus none. H. 02. B. 0*19, least 0'15. Penultimate whorl 

 O0G5. Mouth, height 0'17, breadth 01. 



The generic place of this shell cannot be considered as satis- 

 factorily determined. The whole aspect removes it from Admete 

 and even more from JRissoina, which presents in a stronger form 

 the basal sinus. The absence of an umbilicus removes it from 

 Isapis, of which the I. fenestrata, Carp., has a swelling on the 

 pillar-lip, strongly suggestive of this Australian species. On the 

 whole the general appearance of the shell is liker that of a Fos- 

 sarus than any thing else ; and though Philippi's generic diagnosis 

 of Fossarus (Arch. f. JNaturg. vii. 1, 42) gives an edentulate inner 

 lip as a characteristic feature, yet in Fossarus Adansoni, which is 

 the original type of the genus, there is a blunt tooth and a slight 

 sinus or groove on the front of the pillar. As to the large um- 

 bilicus which is constantly attributed to the F. Adansoni, it is 

 often a mere chink, and occasionally it is quite absent. Of an 

 epidermis, I confess I have never seen a trace. In the absence 

 of animal and operculum it is better to avoid the creation of a new 

 genus, though this may probably be necessary in the end ; and 

 I am glad in this difficult classification to have the support of 

 Dr. J. Grwyn Jeffreys. 



