978 



FRESH-WATER BIOLOGY 



6 (S, 7) 



Shell oval; lip thickened but not reflected; smooth within; no callous 

 deposit Auricula Lamarck. 



The typical Auriculae are not represented in our fauna. A single species, A . 

 pellucens Mke. (Fig. 1406), belonging to the subgenus Auriculaslrum Fischer, is 

 found along the southern Florida coast and keys. 



Fig. 1406. 



7 (S, 6) 



Shell oval; lip thickened, with a single strong ridge revolving longi- 

 tudinally into the aperture Tralia Gray 8 



A single species, T. pusilla Gmel., (Fig. 1407; X i/n), found along the Florida 

 coast and "easily recognized by its pure brown color, three plaits and the single 

 ridge on the inside of the impressed outer lip " (Dall.). 



Fig. 1407. 



8 Shell oblong-ovate; lip thickened by a ridge of callus, simple or denticulate, 

 within the edge; no lirae or longitudinal ridges. 



Subgenus Phytia Gray. 



This group has been usually known as Alexia Gray, but that name is preoccupied 

 and inadmissible. A single species, T. mysoiis Dr., (Fig. 1408; X 23), locally intro- 

 duced from Europe on both the Atlantic and Pacific coasts. The west coast form 

 is usually known as Alexia selifer Cooper. 



Fig. 1408. 



9(4) Foot divided transversely by a sulcus. Subfamily Melampinae . . 10 



10 (11, 16) Shell globose-conic; lip sharp, with a dentate or nodulous caUus 

 within Pedipes Adanson. 



Several species are found on the southern Floridan and Californian coasts 

 and are easily distinguished by their globular form and unusually large parietal 

 tooth. Example, P. unisulcatus Cpr., (Fig. 1409; X 25) from California. 



Shell ovate-conic, oblong, or subfusiform ; outer lip sharp, usually 



lirate within Melampus Montfort . . 12 



Four subgenera: 12, 13, 14, 15. 



Fig. 1409. 

 II (10, 16) 



12 (13) Shell ovate-conoid; spire short; body-whorl very large, broadest 

 above and tapering to the base; lip lirate within. 



Subgenus Melampus s.s. 



The species of this group are abundantly found in the salt marshes and 

 brackish water of both the eastern and western coasts. The shape of the shell 

 and the apertural armature are eminently characteristic. Example, M. lineatus 

 Say, (Fig. 1410; X ij), from the Atlantic coast. 



Flo. 14Z0. 



