MELAMPUS. 11 



Auricula bidentata, Gocld, Inv. Mass. 197, f. 131 (1841). — DeKat, 

 N. Y. Moll. 57, t. V, f. 92, 1, 2, 3 (1843).— Kostek, Chemn. ed. 2, 

 Auric. 41, pi. vi, f. 7-11. 



Not Auricula bidens, Potiez et Michacd, Gal. 201, pi. sx, f. 9, 10. 



Auricula jaumei, Mittre, Rev. Zool. (Mars, 1841), 66. 



Auricula hiplicata, Deshayes, Encycl. Metli. II, 91. 



Melanipus bidcntatus, var. lineatus, Say, p 4G of ed. Binney. 



Mclampas bidcntatus, B, Pfeiffer, Mon. Auric. 46. — Var. a. DeKat /. c. 



Along the whole coast from Xew England' to Texas. A very 

 common shell among the grass of salt marshes near high water 

 mark. 



Animal about as long as the shell, and the foot is transversely 

 bifid ; tentacula somewhat Avrinkled, cylindrical, rather smaller 

 towards the tips, which are obtuse or rounded ; eyes placed at 

 the inner base of the tentacula ; rostrum somewhat wrinkled, 

 nearly as long as the tentacula, bilobate before ; foot, anterior 

 segment emarginate behind, posterior segment bifid at the ex- 

 tremity ; all above, with the exception of the tentacula and 

 rostrum, glabrous, reddish-brown, beneath paler. (Say.) 



The shell when 3'oung is quite pretty, being shining and often 

 variegated by the revolving bands. But few mature shells are 

 met with in a perfect condition. They are usually much eroded. 

 From the toothless outer lip to that bearing a heavy callus ridged 

 with transverse laminae, every intermediate variety is found. The 

 absence of the laminas is equally common in mature and young 

 shells. 



Authentic specimens of this species are still preserved in the 

 collection of' the Academy of Natural Sciences of Philadelphia. 



The original descriptions of Mittre and Deshayes are given in 

 Terr. Moll. lY. I have seen authentic specimens of neither of 

 their shells. The descriptions are merely copied by Pfeiifer, in 

 the works referred to in the synonymy. 



Say designates by the name of lineatus, a form peculiar for its 

 revolving lines or bands and more narrow base of the aperture 

 (vide Binn. ed. p. 85). I have met with none suflBciently marked 

 to form a variety, much less a distinct species. The revolving 



' Gould mentions its being said to have been found living with a 

 Planorbis at Windsor, Vt. If so, it must be adapted to a remarkable 

 difference of station, being usually found near the sea. Pfeiffer also gives 

 Vermont as the habitat, probably on the above authority. 



