Mr. J. Alder on new species of Rissoa and Odostomia. 327 



have the peristome complete, though not quite so conspicuously 

 so as is usual in Rissoa. The animals of the only two species of 

 Odostomia which I have had an opportunity of examining in a 

 living state, O. pallida and O. spiralis, perfectly agree with each 

 other in character, and differ strikingly from Rissoa in having the 

 tentacula and foot extremely short and thick, as well as in the 

 absence of lateral appendages. These characters will probably 

 hold good throughout the genus, but more extended observations 

 are desirable. In the mean time, as no tigure of the animal of 

 this genus has yet been published, I have added an outline of 

 O. spiralis (Plate VIII. fig. 13.) for the sake of comparison with 

 the two animals described above. 



Odostomia cylindrica. Plate VIII. fig. 14. 



Shell nearly cylindrical, white, transparent, smooth and glossy, 

 with four or five rounded whorls, rather flattened near the 

 sutm-e. Apex very obtuse. Two or three faint strise or ridges 

 run across the body whorl on a line with the upper part of the 

 apertm-e. Apertm-e ovate, angulated above. Outer lip thin. 

 Pillar-lip a little reflected, with a shght depression behind it, 

 and a small tooth in the centre of the inner margin. Length 

 rather more than a tenth of an inch ; breadth one- third of the 

 length. 



In shell-sand from Ilfracombe and the Land's End. The sand 

 from the latter place was sent me many years ago by Dr. Turton, 

 but he does not appear to have observed this species. I have also 

 obtained it from sand collected by Mrs. W. Alder at Kilkee, on 

 the west coast of Ireland. 



In form it agrees with jNIr. IMacgiUivray's 0. oblonga, but dif- 

 fers from it in not being ribbed. 



A specimen of this shell in the British Museum is named 

 Turbo nivosus, but I cannot believe it to be the shell described by 

 Montagu under that name, as he takes no notice of any strise, 

 and distinctly says that it has no tooth. That Dr. Turton did not 

 know the Turbo nivosus is evident from his comparing it to Turbo 

 Ulvce in his ' Conchological Dictionary.' 



Odostomia'^ obliqua. Plate VIII. fig. 12. 



Shell ovate-oblong, white, smooth, rather glossy and transpa- 

 rent, with five very oblique whorls, sKghtly rounded and divided 

 by a well-defined suture tapering to a point, which is not quite 

 central, the first whorl being a little twisted upwards. The body 

 whorl is very large, occupying more than two-thirds of the whole 

 length of the shell. Aperture oblong-ovate, contracted to a point 

 at the upper angle. Peristome incomplete. Outer lip very thin. 

 Pillar-lip a little reflected, and with a very oblique internal fold 

 only observable in old specimens. Length two-tenths of an inch ; 

 breadth one-twelfth. Though apparently smooth, young speci- 



