FAMILY COLIMACEA. 41 



very thin and transparent, yellowish or reddish amber, covered 

 with a slight epidermis ; whorls three to three and a half, the 

 last capaciously inflated, aperture large, rounded below, more 

 or less contracted above, Kp simple. 

 Succinea is a herbivorous air-breathing mollusk, restricted in its 

 habitat to the immediate vicinity of water or wet places. It Hves 

 chiefly on mud and flags by the side of rivers, lakes, and pools. 

 The animal is generally rather conspicuously mottled with brown, 

 and the head is peculiarly broad and obtuse, with the tentacles short 

 and stout, particularly the lower pair. Its more important organs 

 are scarcely distinguishable from those of Helix. Its minute palate 

 teeth resemble those of Vitrina. The shell, which is extremely thin 

 and of a transparent yellow or reddish amber-colour, is of an oblong 

 fusiformly ovate shape, with the last whorl sufficiently inflated to 

 cover the large pulmonary sac. Only two British species are ad- 

 mitted by Dr. Gray, and by Forbes and Hanley, S. putris and 

 oblonga. Dr. Pfeiffer increases them to four, by raising to the rank 

 of species two forms, S. elegans and acuta, which have been regarded 

 as varieties of S. putris. A careful examination of the specimens 

 set apart by Dr. Pfeiffer in the Cumingian collection, as the types 

 of these species, induces me to adopt a middle course by regarding 

 the two as one. 



The geographical range of Succinea over the globe compared with 

 that of Vitrina, is altogether different. In the New World, where 

 Vitrina is only known by a single small species in the United States, 

 and, by a distinct representative type, Sinmlopsis, of about a dozen 

 species peculiar to Mexico and the Brazils, Succinea is most abun- 

 dant. Thirty species have been described from the islands of the 

 Polynesian Archipelago, twenty-two from the West Indies, sixteen 

 from BoHvia and Mexico, and about five-and-twenty from the great 

 tract of country commencing with the Southern United States, and 

 passing poleward over Oregon and Greenland to Magellan. From 

 all the more explored lands of the Eastern Hemisphere, in which 

 Vitrince abound, not half the same number of Succinece have been 

 collected. India, China, and the eastern islands contribute sixteen 

 species, Tasmania and AustraHa five, Africa, south and west, twelve, 

 and Europe eight, which are probably reducible to six, the French 

 list, according to M. Moquin-Tandon, including five. 



The animal is somewhat inactive ; it retires habitually into its 

 shell when overtaken by drought, and encloses itself by a slight 

 diaphragm. Dr. Gould, speaking of the Succinea ovalis of Massa- 



