Notes on certain Terrestrial Mollusca. 159 



inferior tentacles ; but doubtless they exist, and would 

 be perceptible in the living animal. 



c. Tail magnified, showing the (retractile?) appendage, at 



the base of which the mucous pore was noticed, — the 

 creeping disk remarkably narrow and long. 



d. Section of lingual membrane ; about 85 rows of plates, 



44-1-44, central plate long, narrow, with a single 

 pointed denticle, slightly indented at the base ; late- 

 rals and uncini similar, having a single long recurved 

 denticle. The dentition somewhat similar to that of 

 H. concava Say {Morse Terr. Pul. of Maine, pi. 5), 

 but the plates longer and narrower. 



e. Buccal plate, arcuate, roundly produced in the centre of 



the cutting edge, in form like that in Helicellinse. 



The character of the animal induces me to believe that this 

 species belongs to Stenopus, of which Guilding (Zool. Jour- 

 iii. 527, 1828) describes the pedal disk and tail as follows : — 

 " Discus gressorius distinctus, linearis, musculis transversis, 

 pedis lateribus multo angustior, veluti in genere Onchidio 

 (unde nomen). Cauda tentaculata, tentaculo subretractali, 

 glandald ad basin posita." 



He adds this remark : " A very remarkable and distinct 

 genus allied to the Linnean Helices, from all of which it differs 

 in the curious contraction of the pedal disk, and the caudal ten- 

 taculum furnished with a gland beneath. They creep slowly 

 and awkwardly, not being able to support the shell, on account 

 of the narrowness of the foot, without proceeding in a meander- 

 ing line." 



The shell under consideration may in several respects be 



compared with Stenopus cruentatus Guild. ; the most marked 

 differences are, that the latter is transversely plicatulate and 

 impressed round the perforation. 



