LAMELLEBRANCHIATA. 109 



AviCULA CORNUELIANA, d'Orbigny. 

 (Plate v., fig. 2.) 



Avicula macroptera, Roem., 1841. Nordd. Ool. Vol. I. p. 86, 



pi. 4, f. 5 (non Lamk.). 

 Cornueliana, d'Orbigny, Pal Fr., Terr. Cret., HI., p. 



471, pL 389, f. 3, 4. 

 Auctorum. 



Pictet and Campiche, Pal. Suisse, St 



Croix, p. 66, pi. 152, f. 14. 



Our Brickhill shell belongs to a round-ribbed type, identical 

 with the one which is abundant in the Schb'ppenstedt Hils Con- 

 glomerat (Brunswick), recognised as the one originally figured by 

 Roemer. 



The French type with sharp and more prominent primary ribs 

 (see figs, by d'Orb. and P. and C.) occurs at Speeton, and in the 

 N. German Neocomian clays. These are varietal differences de- 

 pendent upon habitat. 



The shell is commonly called A. macroptera in Germany, and 

 is sometimes named A. pectinata (Sowerby) in English Cabinets. 



The latter is generally considered a different species, distin- 

 guished by its smaller sharp ribs, with one intermediate rib 

 between each pair of primary ones, while A. Cornueliana has a 

 number of riblets and striae. 



Localities. Brickhill, Tealby, Speeton, Folkestone Gault. 

 N. Europe. Schoppenstedt, Hils Conglom., Bredenbeck. 

 S. Europe. St Croix (Mid. Neocomian). 



PERNA, sp. nov. 

 (Plate V., fig. 3, a, 6.) 



In form similar to the young of Perna (Gervillid) aliformis 

 (Sby.), but the Up ware shell is more oblique, its anterior ear is 

 larger, and no distinct ribs are seen. 



A shell from Shanklin in the Collection of Mr C. J. A. Meyer is 

 very near to this, occurring pretty commonly there where mature 

 aliformis is not found. (Meyer.) 



Locality. Upware (Coll. Mr J. F. Walker, M.A.). 



N. Europe. Oberg, Hildesheim (?), Hils Conglomerat. 



