190 AMERICAN JOURNAL 



ON THE GENERIC POSITION OP HELIX NEWBERRY AN A 



BY THOMAS BLAND AND W. (1. BINNEY. 



Helix Newberryana (Terr. Moll. U. S. IV, pi. lxxvi, fig. 7), 

 has, until now, been of doubtful generic position. In the Check 

 Lists of Shells, published by the Smithsonian, it was placed by 

 one of us in the genus Macrocyclh. Mr. Tryon, in his mono- 

 graph, subsequently followed this suggestion. In Land and 

 Fresh-water Shells of N. A., Part I, we placed the species in 

 the genus Zonites, on account of its resemblance to the European 

 group of Z. algira, &c. An opportunity of examining the jaw 

 and lingual membrane of the species, extracted from a dried 

 specimen, now enables us to decide its true position. We find 

 the species to belong neither to Macrocyclis nor to Zonites, but 

 to be a true Helix. 



The jaw is decidedly costate. The lingual membrane has the 

 arrangement of teeth usual to the Helicidce. The centrals are 

 subquadrate, with a broad reflection, produced into the usual 

 trilobed cusp. The laterals are the same as the centrals, but bi- 

 cuspid and unsymmetrical. The marginals are but a modifica- 

 tion of laterals ; they are low, wide, subquadrate, bearing one 

 long and one short, oblique, stout cusp. 



Had the species been a true Macrocyclis, the jaw would have 

 proved to be without ribs on its anterior surface, and furnished 

 with a median, beak-like projection to its cutting edge. The cen- 

 tral tooth of the lingual membrane would have been small, nar- 

 row, acutely pointed, the lateral teeth would have been entirely 

 wanting, and the marginal teeth would have been replaced by 

 very oblique rows of simply thorn-shaped teeth. (See L. & Fr. 

 W. Shells, Part I, p. 55, fig. 92, p. 57, fig. 96.) 



Had Helix Newberryana proved a true Zonites, we should 

 have found the smooth jaw without anterior ribs, and with a de- 

 cided beak-like median projection on its cutting edge. (See L. 



