276 



LAND AND FRESII-AVATER SHELLS OF N. A. 



Fig. 493. 



[part I. 



The jaw is described by Moquin-Taiidon as moderately arched, 

 of a light tawny color, brownish near the concave 

 margin ; extremities a little attenuated ; anterior 

 ribs about twelve, well marked, especially when the 

 jaw is dry, flattened, marginal crenulations perfectly 

 distinct, very obtuse. 



Lingual membrane broad, teeth 31 — 1 — 31; 

 central teeth tricuspid, laterals bicuspid, uncini with a single 

 cusp. 



¥ur, 404. 



Jaw of 

 Arion fiiscus 



msmm^^, 







Linjjual deutitiou of Arion fuiicus. 



Found near Boston. It is an introduced species common over 

 the whole of Europe. 



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 covered with a watery mucus, and it suspends 

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

 mucous secretion from the terminal pore is transparent and verj 

 viscid. It is not distinguished by any considerable variety of 

 color or markings. It occurs in small numbers in the vicinity 

 of Boston, under stones, at road-sides, in company with Limax 

 a'grestis, 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 M. Ferussac as " griseus, unicolor, fasciis nigris," 

 and had no longer any doubt on the subject. The specimens 

 found in gardens are, however, much larger than the size indi- 

 cated by the descriptions. It is called a small species by both 



