44 COLIMACEA. 



Shell ovate, ventricose ; body and spire of nearly equal 

 length ; the latter consisting of four considerably inflated volu- 

 tions, the three superior ones rapidly diminishing, and termi- 

 nating in a rather sharp apex ; aperture subovate ; outer lip 

 slightly reflected, and white ; pillar lip narrowly reflected on 

 the columella, with a narrow subumbilicus behind it ; whole 

 surface covered with a chestnut-brown epidermis. Length not 

 two lines ; diameter equal to two-thirds its length. 



Found at Portmarnock, Ireland. 



This species is much shorter, in proportion to its breadth, 

 than the P. marginata, and is always destitute of the rib be- 

 hind its outer lip. 



Notwithstanding the opinion of Rossmassler and other 

 authors, I always have considered that the P. muscorum, 

 unidentata, and hidentata are distinct species ; for besides the 

 dentition, the following distinctions will be found in the three 

 nearly allied species of this genus. In P. muscorum the shell 

 is subcylindrical, the whole volutions a little more oblique than 

 in the other species, and gradually decreasing, with the apicial 

 one rather obtuse; and the body and first volution longer. P. 

 unidentata is nearly cylindrical, the volutions are more trans- 

 verse, the three apicial ones diminishing more abruptly, with 

 the superior one more pointed. P. bidentata is altogether a 

 shorter shell in proportion to its breadth. 



4. Pupa marginata, pi. V, f. 4, 5. 



Pupa marginata, Drapernaud, Hist, des Moll., p. 61, pi. 3, 

 f. 36, 37, 38; PfeilTer, Land un Was. Sn., I, p. 59, pi. 3, f. 23, 

 24; Brard, p. 93, pi. 3, f. 15, 16; Turton, Man., p. 98, f. 79; 

 Jeffreys, Linn. Tr., XVI, p. 358 ; Thompson, Ann. and Mag. 

 Nat. Hist., VI, p. 25 ; Forbes, Mai. Mon., p. 11 ; Pupa mus- 

 corum, Lamarck, VI, p. Ill ; Rossmassler, VI, p. 15, pi. 23, 

 f. 5 ; Turbo muscoruyn, Brown, Ency. Brit., 6th Ed., VI, p. 

 457; Turbo tnarginata, Sheppard, Linn. Trans., XIV, p. 154; 

 Pupilla marginata, Leach, Moll., p. 1 27 ; Alcsa marginata, 

 Jeffreys, Linn. Tr., XVI, p. 357 ; Pupa marginata, Brown, 

 Illust. Conch., p. 39, pi. 18, f. 33, 34. 



Shell glossy, subpellucid, cylindrical, of a chestnut-brown 

 colour; body about a third of the length of the shell; spire 

 consisting of five or six slightly inflated, convex volutions, well 



