180 INVERTEBRATA OF MASSACHUSETTS. 



throat with two or more pairs of teeth ; umbilicus broad and 

 deep. 



FIGURE 103. 



State Coll., No. 108. Soc. Cab., No. 2393. 



Helix lineata, SAY ; Journ. Acad. Nat. Sc., i. 18, ii. 273. FERUSSAC ; Hist. Nat. 

 des Moll., pi. 79, f. 1. BINNEY ; Bost. Journ. Nat. Hist., iii. pi. 29, f. 3. 



Shell minute, discoidal, flat above, concave beneath, greenish ; 

 whorls about four, flat above, higher than broad, separated by a 

 distinctly impressed suture, covered with numerous, parallel, 

 raised, revolving lines ; otherwise smooth ; aperture narrow, 

 semi-lunar ; lip simple and thin ; umbilicus wide and deep, ex- 

 hibiting each volution to the apex. Within the aperture, on the 

 external wall, are placed two pairs of white, conical teeth, the 

 first pair in sight on looking into the aperture, the other more 

 remote, and seen only through the semi-transparent shell. Di- 

 ameter one eighth of an inch, usually less. 



Animal whitish, transparent, thread-like. 



Found in this, and all the other New England States, and in 

 Pennsylvania. It has been noticed, for the most part, under the 

 bark, or in the interstices, of rotten wood ; sometimes under 

 stones and leaves in damp places. 



At first sight, one would be disposed to call this shell a Planorbis 

 rather than a Helix. Perhaps it is the P. paralUlus, of Say. Its 

 wheel-shaped form, greenish color, revolving raised lines, and singular 

 teeth, are characters which cannot be mistaken. One pair of these 

 teeth may always be found and seen ; and in one instance Dr. Binney 

 noticed even a third pair still farther within the whorl. 



HELIX CELLARIA. 



Shell orbicular, depressed, thin, pellucid, glistening, smooth ; 

 whorls five, flattened ; aperture rounded ; lip simple ; umbilicus 

 deep. 



FIGURE 104. 

 State Coll., No. 97. Soc. Cab., No. 1059. 



Helix cellkria, MULLER ; Verm. Hist., No. 230. CHEMN. ; Conch., ix. t. 127, 

 f. 1129, 1,2. FERUSSAC; Hist. Nat. des Moll, No. 212. DESHAYES; Encyc. 



