70 EOCENE MOLLUSCA. 



they are not continued towards, and do not appear at, the aperture. The columellar 

 lip does not present any evidence of teeth. The umbilicus is rather small. 



On comparing this shell with H. labyrintldca, the distinctions appear to be that, in 

 the present species, the apex is more obtuse, approaching, in that character, more nearly 

 to the recent specimens of that species ; the whorls enlarge more slowly, are more 

 roundedly convex, and but slightly, if at all, flattened on the base ; the aperture, 

 partaking of the character of the whorls, is rounder, and the teeth, if present, are on 

 the outer lip, and not on the columellar lip, as in II. labyrintldca ; the umbilicus is 

 smaller, and, if the shell were preserved, would, I think, be nearly closed. 



Having only seen the single specimen in my collection, I propose the species with 

 hesitation, although the characters seem to me sufficient for specific distinction. 



Size. — Elevation 1-1 0th in. nearly; diameter l-10th in., nearly. 



Locality. — Headon Hill. 



No. 22. Helix Headonensis. F. E. Edwards. Tab. XI, fig. 5 a — d. 



H. testa minutd, orbiculari, sub-depressd, umbilicatd ; spird prominuld ; anfractibus sex, 

 rotundatis, suturis perspicuis : aperturd rotundato-semi-lunari, obliqud ; perislomate incras- 

 sato, reflexo ; margine externo tribus lamellis, penitissime decurrentibus, instructo : umbilico 

 lato, prof undo. 



A very small depressedly orbicular shell, with a somewhat elevated spire, com- 

 posed of six or seven rounded whorls, separated by a deep suture ; the rounded 

 aperture is oblique, and impinged upon by the body whorl, which gives to it a semi- 

 lunar shape ; the peristome is slightly thickened internally, and reflected ; and the outer 

 lip is furnished with three lamelliform teeth, extending far back into the whorls ; the 

 umbilicus is wide and deep. 



The //. Headonensis is apparently extremely rare ; my specimen, which I believe to 

 be unique, is merely a cast, and the outward condition of the shell is not shown. The 

 species presents some analogy with the depressed variety of H. labyrintldca ; but the 

 greater number of the whorls, and the different dentition of the aperture, distinguish it 

 from that shell. In general appearance it resembles the recent H. pulcltella ; but the 

 spire is more elevated, the whorls more numerous, and, in the latter species, the 

 aperture is without the plaits which characterise the present shell. The species 

 appears to be well marked and perfectly distinct. 



Size. — Elevation rather more than l-20th in. ; diameter 1-1 0th in. 



Locality. — Headon Hill. 



