CRETACEOUS PERIOD. 101 



revolving striae are obsolete. Occasionally also a few incipient vertical 

 costae are to be seen npon the body volution of large specimens. 



Length of the largest example in the collection, from the apex of the 

 spire to the end of the anterior canal, thirty millimeters. 



Mr. Meek's type-specimens being incomplete, he was in doubt whether 

 they ought to be refen-ed to the genus AncJmra or not. The examples under 

 consideration will not enable me to decide the question now. The presence 

 of a little callus preserved at the posterior portion of the aperture of one of 

 our examples suggests the probable presence of a posterior canal ; in which 

 case the shell cannot be assigned to Anchura, but probably belongs to the 

 genus IleUcaulax Gabb. 



Position and locality. — Strata of the Cretaceous period: east bank of Rio 

 Puerco, six miles below Casa Salazan ; six miles west of Seboetto; and Cerro 

 Rotunda, New Mexico. 



Genus LISPODESTHES, nov. gen. 

 Etym. — itV-o?, smooth, and £(t(?)j?, a garment; in allusion to the callus-covered spire. 



Shell fusiform ; anterior canal straight or slightly ciirved, and more or 

 ■ less produced ; posterior canal extending nearly or quite the whole length 

 of the spire, from near the apex of which it may be a little deflected ; aper- 

 ture winged ; wing rather large, bearing two processes ; the posterior pro- 

 cess spine-like or falciform; the anterior process either in the form of a lobe 

 or tongue-shaped ; inner lip and spire covered with callus. 



This genus is related to Helicaulax Gabb, and may possibly prove to 

 be only subgeuerically distinct from it. It differs from that genus in having 

 the callus enveloping the whole spire instead of extending along the under 

 side only, and also in the pi-esence of the moderately large anterior process 

 of the wing. In some respects it is like Calyptroplionis Conrad, but it differs 

 conspicuously from that genus in having two prominent processes to the 

 wing instead of being plain, thickened, rounded, and smooth. Besides this, 

 the form is not so elongate as is common in that genus. 



Only two species of this genus, so far as I am aware, have been dis- 

 covered in the Cretaceous strata of North America, both of which are 

 described in this report. 



