462 A MANUAL OF AMERICAN LAND SHELLS. 



Arion fuscu>t, Moquin-Tandon (which see for further foreign synonyms). — W. G,. Bix- 

 NEY.L. & Fr.-W. Sh.. 1, 275 (l-'69); Terr. Moll., v, 224.-Tryon, Am. Journ. 

 Conch., iii, 316 (18(58). — Gould and Binney, Inv. of Mass., ed. 2, 451 (1870). 



Found in the city of Boston. It is an introduced species, common 

 over the whole of Europe. Has also been introduced into Greenland 

 (see Morch, Am. Journ. Conch., IV, 37). 



When the animal is fully extended the mantle occupies less than a 

 fourth part of its whole length, and the dark lines on the mantle and 

 back are continuous with each other. The head only projects from 

 the mantle, the neck not being visible. Its surface is constantly cov- 

 ered with a watery mucus, and it suspends itself with a thread of mu- 

 cus, like the other species. The mucous secretion from the terminal 

 pore is transparent and very viscid. It is not distinguished by any 

 considerable variety of color or markings. It occurs in small numbers 

 in the city of Boston and vicinity, under stones, at road-sides, in com- 

 pany with Limax agrcstis, and more plentifully in gardens within the 

 city. In the remarks on this species formerly published by Dr. Bin- 

 ney he hesitated in considering it to be identical with the foreign spe- 

 cies of the same name. Having later found it somewhat numerous in 

 a locality in Boston, he procured specimens agreeing verj^ well with 

 foreign descriptions and figures, especially with that variety described 

 by Ferrusac as g rise us, unicolor, fasciis nigris, and had no longer any 

 doubt on the subject. The specimens found in gardens are, however, 

 much larger than the size indicated by the descriptions. It is called a 

 small species by both Ferussac and Lamarck, and so it is as it exists 

 in the country; but in the city it is sometimes two inches in length, 

 when not fully extended, and of a corresponding bulk. The dark 

 lines are most strongly marked in the large variety. The small vari- 

 ety is more delicate in its markings and has a tinge of yellow on the 

 foot. It is s'till restricted in its distribution, so far as known, to the 

 neighborhood of Boston alone. 



For jaw and dentition see p. 460. 



The generative system (figured by Leidy, I. c.) resembles more that 

 of Limax variegatus than the other species. The penis sac is cylindri- 

 cal, dilated at base, and has its retractor muscle inserted into the latter 

 point. The genital bladder is large, oval, pointed at summit, and has 

 a very short but muscular duct, joined midway by the vagina. At the 

 latter junction is inserted a second retractor muscle. The cloaca is 

 long and dilated in the middle. 



