452 ARIONID^. 



furrows on each side. The triangular miicus-pore is on the upper 

 surface of the jiosterior extremity, is very apparent, and has a i)ro- 

 cess of the skin which seems to cover it, and sometimes to project 

 above it. When fully grown the extreme length is more than iifty 

 mill., its usual length about twenty-five millimetres. 



Internal granulations coarsely united or aggregated into a some- 

 what ovular, semi-transparent, very granular plate. 



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

 a foiu'th part of its whole length, and the dark lines on the mantle 

 and back arc continuous with each other. The head only projects 

 from the mantle, the neck not l)cing visilile. Its surface is con- 

 stantly 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 very viscid. 



It is not distinguished by any considerable variety of color or 

 markings. It occurs in small numbers in the vicinity of Boston, 

 imder stones, at roadsides, in company with Liinax agrcslis, and 

 more plentifully in gardens within the city. In the remarks on this 

 species, formerly published by Dr. Binney, he hesitated in consider- 

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

 Having since found it somewhat numerous in a locality in Boston, 

 he procured specimens agreeing very well with foreign descriptions 

 and figures, especially with that variety descriljed by M. Ferubsac 

 as '■'■ g-riscus, nnicohr.fascus nig-ris,'" 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 M. Ferussac and U. Lamarck, and so it is, 

 as it exists in the country ; Ijut 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 vari- 

 ety. The small variety is more delicate in its markings, and has a 

 tinge of yellow on the foot. It is still restricted in its distribution, 

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



Oeiiiis ZOIVITES, IMontfort. ISIO. 



Shell broadly umbilicated, orbiculate, convex or discoidal, stri- 

 ated or decussated, beneath smooth and shining ; whorls six or 

 seven, gradually increasing in size ; aperture ol)lique and lunate ; 

 peristome straight, acute, and slightly thickened internally. 



Animal with a caudal nuicus-pore. 



