J. S. GARDKER ON BRITISH CRETACEOUS PATELLID.^ ETC. 195 



described and figured in the ' Ann. and Mag. Nat. Hist.' for April 

 1861. The figure is unfortunately not very accurate. 



Helcion Meyeri, sp. nov. Lower Greensand. PI. VII. figs. 8-11. 



Cap-shaped, depressed, anteriorly convex, posteriorly excavated ; 

 apex recurved, posteriorly projecting beyond the margin; sculpture, 

 about twenty-two strong, rounded, imbricated ribs. 



This unique shell was found by Mr. Meyer in the Folkestone 

 beds of the Lower Greensand at Shanklin. It is an undoubted 

 Helcion, and represents the earliest known appearance of that genus, 

 which had not previously been found fossil. It bears a distant re- 

 semblance to Emarginula Desori, P. & C. The figure should have 

 represented the shell as symmetrical. 



Antsomton vectis, sp. nov. Xeocomian. PI. IX. figs. 3, 4, 5. 



Oval, slightly quadrate, elevated, thin ; apex small, pointed, sub- 

 central, placed rather anteriorly ; surface smooth or polished, without 

 radiating ribs or lines, but with concentric, parallel, undulating 

 lines of growth. 



This species resembles Helcion (Acmcea) conicum of D'Orb., from 

 the Upper Gault, and Tectwra elevata*, Forbes, figured by Stoliczka 

 in the ' Pal. Indica,' but is thinner and more delicate than either. 



Anisomyon is a Cretaceous genus, founded by Meek and Hayden f. 

 The specimens just described cannot be examined interiorly ; so that 

 the form of the muscular scar is unknown ; but the smooth aspect, 

 thin shell, and minute apex leave little doubt they are correctly 

 placed in this genus. 



Two specimens are known, which were obtained from the Cracker 

 Rocks of Athcrfield, and are now in the Woodwardian Museum. 



Sctjrria calyptr^lformis, sp. nov. Lower Greensand. PI. VII. 

 figs. 15, 16. 



Shell ovate, or suborbicular, elevated, convex posteriorly, rather 

 flattened anteriorly ; apex anterior, slightly obtuse. The cast near 

 the margin retains traces of fine radiating ribs, but is otherwise 

 smooth, with irregular lines of growth. 



The specimen, now in the British Museum, has a Calyptrcea-YikQ 

 aspect, but resembles most strongly Scurria mitra. It is from the 

 Lower Greensand of Seend. 



Scitrria depressa, sp. nov. Lower Greensand. PI. VII. fig. 17. 



Of the same form as the last species, slightly more depressed, but 

 with an entire margin without the least trace of ribbing ; more 

 specimens may establish their identity. Two specimens are in the 

 British Museum, which were found with the last. 



* Geol. Soc. Museum. 



t 'American Journal of Science and Arts,' May I860 (2nd ser.), vol. xxix. 



02 



