OF CONCHOLOGY. 145 



carbonaris, by the single digitate process at the upper, outer 

 angle of the very thick lip, and finally by both species being 

 angulated at the lower part of the lip, and having a groove ra- 

 diating to that angle, showing the suppressed tendency to the 

 formation of another process, which does not exist. 



Subgenus ARRHOaUS, Gabb. 



Shell fusiform, anterior canal nearly obsolete, no posterior 

 canal, outer lip expanded, simple. 



A. (A.) occidentalis, Beck. Living only. 



Genus ANCHURA, Con. Plate 14, fig. 13, 14. 

 (Drepanocheilus, Meek. Perissoptera, Tate.) 



Fusiform, anterior canal straight, more or less produced ; no 

 posterior canal ; onter lip produced into a single process, falcate, 

 or sometimes bearing a spur below as well as above. 



A. abrupta, Con., A. carinata = Rostellaria carinata, Mantell, 

 A. falciformis = Aporrhais id, Gabb. A large genus, numerously 

 represented in the upper and lower secondaries. 



Drepanocheilus was evidently based on a misapprehension of 

 Mr. Conrad's diagnosis and figure, since the principal character 

 on which Mr. Meek insists is the absence of the posterior canal, 

 — one of the most marked features of the present genus. It is 

 unfortunate that a form which has since proved aberrant in the 

 genus should have been chosen as its type ; the T-shaped lip of 

 abrupta and carinata is not a character for generic, or even sub- 

 generic division, inasmuch as other species show almost every 

 gradation from this to the falcate form, which is by far the more 

 common. 



Genus HELICAULAX, Gabb, n. gen. Plate 14, fig. 15. 



Shell like Ancliura, but with a long posterior canal ascending 

 the spire to near the apex, usually deflected near its extremity ; 

 inner lip usually heavily encrusted, the callus sometimes extend- 

 ing some distance up the spire. 



H. ornata = Rostellaria id., d'Orb., H. Buchii = Rostellaria 

 Buchii, Munst., II Pyrenaica = Rostellaria Pyrenaica, d'Orb. 

 Cretaceous. 



In a somewhat mutilated specimen of an undescribed species 

 of this genus, from California, the outer lip is biangular, the 

 hook-like prolongation is short, but I have not the means of 

 knowing whether or not the lower angle was prolonged. 



