414 A MANUAL OF AMERICAN LAND SHELLS. 



delicate ribs upon its snrfiice. There are over 50 ribs on tlie jaw of 

 the only one of our species I have examined, ilf. Gossei. I give a copy 

 of Mr. Bland's figure of the jaw of J7. signatus, which is similar. 



The lingual membrane of Macroceramns was supposed to be the 

 same as in CylindreUa, described a.bove, as that of M. signatus was so 

 found by Mr. Bland (Ann. Lye. Nat. Hist. N. Y., VIII, 162) and 

 Crosse and Fischer (Journ. de Conch., 1870, Plate III, Figs. 14-16). 

 It was, therefore, with surprise that I found an entirely different type 

 of dentition in M. Gossei. I can in this place only note the difference, 

 and leave to future study the question of its bearing on the generic 

 position of the species. 

 M. Gossei (Plate X, Fig. Q, of Terr. Moll.; see Fig.455)hasa membrane 

 riG.455. very long and narrow; teeth about 40-1-40, in 



scarcely oblique transverse rows, decidedly not en 

 chevron. Centrals with a long, narrow base of at- 

 tachment, with somewhat expanded lower lateral 

 angles, its upper margin squarely reflected. The 



Lingual dentition of 



M. Gossei. reflected portion is very small, and bears three 



short, blunt cusps, the median the largest, all three with distinct 

 cutting points. The base of attachment of the laterals is long and 

 narrow, its outer lower angle irregularly cut away; the upper margin 

 broadly and obliquely reflecte<l, the reflected portion thrown off' ob- 

 liquely towards the margin of the lingual membrane, very short, and 

 bearing two stout, bhmt, short cnsps, the inner the larger, also thrown 

 obliquel}' towards the outer margin of the membrane; both of the 

 cusps bear distinct cutting points, the outer one small, the inner one 

 narrow, blunt, almost as long as the base of attachment. There are 

 no distinct marginals, the laterals decreasing in size as they pass off 

 laterally, those at the edge of the membrane having one large inner 

 cutting point and several outer, irregular, smaller ones. I have given 

 a group of centrals and laterals, a group of laterals, and an extreme 

 lateral or marginal.* 



I have had no opportunity of examining M. pontificus. 



Maci'ocorainus pontificiis Gould. 



Shell fusiform, attenuated-cylindrical, whitish, or grayish clouded 

 and marbled with brown; spire acuminate; whorls from 9 to 13, 



* Similar deutition is found in M. turricula, Pfr., of Cuba. See ]Proc. Acad. Nat. Sci. 

 Pbilad., 1875, Plate XX, Fig. 9. 



