ARION. 225 



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 con- 

 tinuous with each other. The head only projects from the mantle, the neck 

 not being visible. Its surface is constantly covered with a watery mucus, and 

 it suspends itself with a thread of mucus like the other species. The mucoii9 

 secretion from the terminal pore is transparent and very viscid. It is not dis- 

 tinguished by any considerable variety of color or markings. It occurs in small 

 numbers in the city of Boston and vicinity under stones, at roadsides, in com- 

 pany with Limax agrestis, and more plentifully in gardens within the city. In 

 the remarks on this species, formerly published by Dr. Binney, he hesitated 

 in considering it to be identical with the foreign species of the same name. 

 Having later found it somewhat numerous in a locality in Boston, he procured 

 specimens agreeing very well with foreign descriptions and figures, especially 

 with that variety described by Ferussac as griseus, unicolor, fasciis nigins, 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 variety is more delicate in its mark- 

 ings, and has a tinge of yellow on the foot. It is still restricted in its distribu- 

 tion, so far as known, to the neighborhood of Boston alone. 



For jaw and dentition see p. 223. 



The generative system (figured by Leidy, 1. c.) resembles more that of 

 Limax variegatus than the other species. The penis sac is cylindrical, 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. 



Spurious and Doubtful Species of Arion. 



Arum (Lochea) empiricorum is quoted without authority or description from the 

 Western States by Grateloup (Distr. Geogr. de la Famille des Limaciens). 



Ario,i foHolafus, Qovld (Vol. III. PI. LXVI. Fig. 2). Color a reddish-fawn, 

 coarsely and obliquely reticulated with slate-colored lines forming areolre, which 

 are indented at the sides, when viewed by a magnifier, so as to resemble leaf- 

 lets ; the mantle is concentrically mottled with slate-color, and the j'rojecting 

 border of the foot is also obliquely lineated. The body is rather depressed, 

 nearly uniform throughout, and somewhat truncated at the tip, exhibiting a 

 conspicuous pit, which was probably occupied by a mucus gland. The mantle is 

 very long, smooth, and has the respiratory orifice very small, situated a little in 

 front of the middle. The eye-pedunclea are small and short. Length, 85 mill. 



VOL. IV. 15 



