2 CRETACEOUS LAMELLIBRANCHIA. 



Affinities. — D'Orbigny 1 considered that this species was identical with his 

 N. liiujulata ;~ but that form was founded on a cast, so that an exact comparison 

 cannot be made. N. lingulata, however, appears to be more pointed posteriorly 

 and to taper more regularly than N. spathulata; it is also shorter anteriorly. 

 N. sjpathulata is distinguished from JSf. solea (d'Orbigny) by its ornamentation 

 and less elongate form. 



Remarks. — This appears to be a rare species; I have seen only six examples 

 of it. Several of the specimens recorded by Gardner do not belong to this 

 species, but to N. scapha (d'Orbigny) (see p. 4). The example from Speeton 

 which he figures may be N. spathulata, but it is in the form of a cast, and the 

 posterior part is not perfect. 



Types. — The type (PI. I, fig. 1) is an internal mould, but shows indications of 

 the ribbing ; it comes from the Atherfield Clay, and is in the collection of the 

 Geological Society of London (No. 2112). 



Distribution. — Crackers of Atherfield; Atherfield Clay of Atherfield; 

 ? Speeton Clay of Speeton. 



Nuculana suBRECDRVA (Phillips), 1829. Plate I, figs. 4 a — c, 5 a, b.. 



1829. Nucula subuecurva, J. Phillips. Geol. Yorks., pt. 1, p. 122, pi. ii, 



fig. 11. 

 1854. — J. Morris. Cat. Brifc. Foss., ed. 2, p. 217. 



I860. — — F. J. Pictet and G. Campiche. Foss. du Terr. 



Cret. des Envir. de Ste. Croix 

 (Matur. Pal. Suisse, ser. 4), pt. 3, 

 p. 401. 

 1884. Leda stjbrecurva, J. S. Gardner. Quart. Journ. G-eol. Soc. vol. xl, 



p. 135, pi. v, figs. 24, 25. 

 Nou 1844. Npcula stjbrecurva, A. d'Orbigny. Pal. Franc. Terr. Cret., vol. iii, 



p. 170, pi. ccci, figs. 7—11. 



— 1850. Leda subrecurva, d'Orbigny. Prod, de Pal., vol. ii, p. 136. 



— 1867. — — O. Fraas. Aus dern Orient, pt. i, p. 92. 



Description. — Shell inflated, elongate, inequilateral, the posterior part being 

 much longer than the anterior; ventral margin gently curved; extremities 

 rounded; posterior part wedge-shaped ; anterior part narrow. Lunule depressed, 

 not distinctly limited. Surface with concentric grooves and concentric striee. 

 Measurements : 



Length . . . 18 . . 18 mm. 



Height . . . 10. . . 11 „ 



Thickness . . . 10 . . 11 ,, 



1 'Prodr. de Pal.,' vol. ii (1850), p. 117. 



2 'Pal. Franc. Terr. Cret.,' vol. iii (1814), p. 16S, pi. ccciv, figs. 1—3. 



