OF CONCHOLOGY, 187 



ON THE LINGUAL DENTITION OF MACROCERAMUS 

 GOSSEI, PFR. 



BY THOMAS BLAND AND W. G. BINNEY. 



We are indebted to Mr. Vendryes for numerous Jamaica speci- 

 mens of this species, from which we extracted the jaw and lin- 

 gual membrane here described. 



Jaw arcuate, thin, light horn color, almost transparent, in nu- 

 merous separate plates (over fifty), of the character peculiar to 

 the species of Cylindrellidce, as described by Messrs. Crosse and 

 Fischer, in the Journal de Conehyliologie, Jan., 1870. 



Lingual membrane long and narrow ; teeth about 40 — 1 — 40, 

 in scarcely oblique transverse rows, decidedly not en chevron. 

 Centrals long, narrow, somewhat expanded at base, narrowing 

 towards the apex, which is reflected and produced into a short, 

 stout, bluntly-pointed beak. Laterals long, laminar, their outer 

 edge often cut away irregularly towards the base ; upper edge 

 inclined obliquely toward the centrals, broadly reflected and bi- 

 cuspid, the inner cusp the larger, and produced into a very long, 

 narrow, acutely-pointed beak. Marginals of the same type as 

 laterals, decreasing in size as they pass outward ; those at the 

 edge of the membrane having one large inner cusp, and several 

 outer, irregular, small cusps. 



Figure 11 gives the central and several laterals of two adja- 

 cent rows of teeth. Figure 9 gives a single lateral, more highly 

 magnified. Figure 12 gives an extreme marginal. Plate 17. 



From the above description and the figures, it will be seen 

 that this species differs in its lingual dentition from Macrocera- 

 mus signatus, already described and figured by one of us (Bland, 

 Ann. N. Y. Lye. VIII, 162). A reference to the paper of 

 Messrs. Crosse and Fischer, quoted above, shows further that 

 this lingual membrane differs entirely from that of any species 

 of Cylindrellidce as understood or adopted by them. 



