Mr. L. Reeve on thn genus Scarabus. 219 



genus Auricula. Lamarck, however, like his predecessors, ap- 

 pears to have referred all the varieties then known to one 

 particular species. Auricula scarabcms {Helix scarabceus, Lin- 

 naeus, Bulimus scarabcBus, Bruguiere). Not so De Ferussac : 

 a variety which had been figured by Chemnitz was very pro- 

 perly distinguished by this author by the name of Scarabus 

 plicatus ; he appears indeed to have been the first to appre- 

 ciate the genus in question. Two other species were then in- 

 troduced by Lesson in his ' Zoologie de la Coquille,^ and we 

 are indebted to this naturalist for establishing the importance 

 of the genus by further demonstrating a difference in their 

 organization and habits. The Auriculce are partially aquatic, 

 and are for the most part found in wet and marshy places on 

 the banks of lakes and rivers, or even on the sea-shore ; the 

 Scarabi, on the contrary, are inhabitants of a dry soil, loca- 

 ted at the roots of trees in the very centre of woods and 

 forests. 



The following are eleven species, all of which, with one ex- 

 ception, I have succeeded in identifying. 



1. Scarabus clausus. Nobis. 

 Helix clausa, Wagner. 

 Helix tomogera, Moricand. 

 Auricula clausa, Michaud. 

 Tomogerus clausus, Spix. 



The aperture of this shell is nearly closed by the strong denti- 

 tion which is characteristic of the genus. (Plate IV. fig. 1.) 



2. Scarabus trigonus, Troshel, Wiegmann's Archiv, 1840. 



This shell, recently described by Dr. Troshel of Berlin, is of very 

 remarkable growth, the last whorl being suddenly contracted to the 

 form of a sharp angle. The species altogether is highly characteristic, 

 and cannot fail to be recognised. (Fig. 2.) 



3. Scarabus plicatus, De Ferussac, Prodrome, p. 101 ; Chemn. 



Conch., vol. ix. pi. 136. f. 1252 and 1253. 



Helix scarabceus, var. Chemnitz. 



Auricula plicata, Deshayes. 



Chemnitz's figure of this species is cited as a variety both of the 

 Helix scarabceus of Linnaeus, and the Cochlea Bengalensis of Petiver. 

 It may be distinguished however from both by the angular direction 

 of the last whorl, though it is far less characteristic than in the Sca- 

 rabus trigonus. (Fig. 3.) 



4. Scarabus undatus. Lesson, Voyage de la Coquille, Zoologie, 



vol. ii. p. 336. pi. 10. f. 6. 

 Auricula scarabceus, var. Deshayes. 



I only know of two specimens of this shell, both sufficiently distin- 

 guished by the waved lines which irregularly cross each other on the 

 back. I believe this character exists only in the epidermis, which is 

 unusually thick, but am satisfied of the identity of the species by a 

 distinct peculiarity in the general formation of the shell. Deshayes 



Q2 



