Tornatellidse, and Pyraniidellidse. 451 



be mentioned. Then, M, Loven^s Aclis next succeeds as a Pyra- 

 midellar genus, and only embraces one or two species. The 

 Truncatella of Risso, the animal of which has been described by 

 Mr. Lowe, will complete the British genera of the PyramidellidcB, 

 and admit a small number of species which either become more 

 or less decollated, or have dome- or button-shaped apices. 



As the above enumeration is not exactly in natural order, we 

 state that the genera will stand thus : Truncatella, Chemnitzia, 

 Eulima, Aclis, and Stylifer ? They follow in natural order the 

 Conovulidce and Tornatella, with, as we have already stated, the 

 lateral abutment of the Littorina, Trochi, Cerithia and Turri- 

 tellce, and are followed by lanthina, Scalaria, Natica, Velutina, 

 and Laminaria, all of which having a recondite proboscis, form 

 the passage to Cerithiopsis and the Muricidal Canalifera. I have 

 only mentioned this rough section of natural order, which 

 perhaps may be modified, as a cursory view of the position of 

 this interesting tribe. 



Truncatella, Risso. 



T. Montagui, Lowe, Zool. Journ. vol. v. p. 209. 



I have never seen the animal of T. Montagui, the type, but it 

 fortunately has been observed by a most competent malacologist, 

 Mr. Lowe, who informs us that the animal has an extended bi- 

 lobed muzzle, two contractile, subconical, short, obtuse, divergent 

 tentacula, having sessile eyes a little above, but at the external 

 bases. The mantle has a collar as in Helix. A very short foot, 

 subtruncate in front, rounded behind, and by M. Deshayes^ ac- 

 count transversely divided in the sole. M. Philippi doubts this : 

 these characters are from the naturalist just named, as I have 

 not by me Mr. Lowe's account in vol. v. Zool. Jom-n. Though 

 this species, by the elongated bilobed head, has alliance with the 

 RissocB, it is by the divided foot — if that is so — much nearer to 

 the Conovulns bidentatus ; and by the sessile position of the eyes, 

 short, subconical tentacula, and simple corneous operculum, it 

 is connected so intimately with the Pyramidellar genus Eulima, 

 as to justify us in considering it and Conovulus one of the points 

 of passage to the genus Chemnitzia. 



Chemnitzia, D'Orbigny. 



Odostomia, auctorum. 



It is unnecessary to insert the specific characters of the animal 

 of this genus ; they will be sufficiently collected from our nume- 

 rous descriptions ; but we cannot refrain from alluding to the 

 Rev. T. Lowe's account of the animal of his genus Parthenia, 

 which is fully borne out by our notes, or rather it bears them 



30* 



