Mr. J. Paget on a new Helix and a new Hydi'obia. 455 



gated form, by its smaller number of whorls wliicli are less 

 convex and divided by a much shallower suture, by its last whorl 

 more ventricose and never detached, by its mouth less rounded, 

 more oblique and more angular, and by the presence of only one 

 swelling behind the mouth, whereas in the H. gibba there are 

 generally several in adult specimens. 



I have found this Hydrobia in the stream below the mill of 

 Davigo, and in a ditch at the Grenouilleres, both of which are 

 supphed from the Var, near Nice. They are attached to the 

 underside of aquatic plants or the underside of stones, and are 

 very plentiful. 



The observations I have made on some of the Pupce of the 

 south of France induce me to believe that too much importance 

 has been given to the teeth as a specific character in this genus. 

 The Pupa cinerea, which is described as possessing six teeth, 

 viz. two parietal, two columella!', and two palatal, and is consi- 

 dered as presenting no variety except in size, I find on the con- 

 traiy with five, six, seven, and eight teeth. In the first case, one 

 of the columellar teeth are wanting, and in the two latter there 

 are either one or two additional teeth on the palate. One of the 

 additional teeth, and the one most commonly found, is placed in 

 the columellar angle of the palate, the other near the external 

 angle. This latter, when present, is commonly indicated by a 

 white hne externally. These variations in the number of 

 teeth are found both in the small and large varieties of Pupa 

 cinerea, and as I have collected at least a dozen of each in this 

 neighbourhood (Nice), they cannot be considered \e.vy rare. 



The variety of Pupa quadridens, in wliich only three teeth 

 exist, has been formed into a species under various names, as 

 P. Niso of Risso, P. seductilis of Ziegler, P. lunatica of Jan, and 

 yet, in the neighbourhood of Montpellier, I have found every 

 shade of variety, from the four teeth of the type, insensibly passing 

 through the three teeth of this false species to a still more im- 

 perfect variety with only two teeth. In like manner the addition 

 of one or two supplemental teeth in the Pupa secale has given 

 rise to the Pupa Boileausiana of De Charpentier, although I have 

 specimens from Montpellier in which eveiy step of the transition 

 may be found. The same observation may be extended to Pupa 

 variabilis, P. inuscurum, P. umbilicata, and probably to many 

 other species, in which the number of the teeth is very uncer- 

 tain, and in which, therefore, as a specific character, they can 

 only be adopted with great caution. 



Another variety of Pupa cinerea common here, which I have 

 not seen noticed, is marked by a red band running parallel to 



