32 CRETACEOUS LAMELLIBRANCHIA. 



weaker posteriorly. The sides of the ribs are ornamented with fine radial ribs, and 

 at the summit there is sometimes a rib with pointed projections. Concentric 

 growth-lines are present. 



Measurements : 



(1) (2) (3) (4) (5) (6) 



Length 39 34 29 29 28 17 mm. 

 Height 1 28 23 20 18 20 12 



(1, 4) Gault, Black Ven. 

 (2, 3, 5, 6) Gault, Folkestone. 



Affinities. Lima Iteriana, Pictet and Roux, 2 appears to differ from this species 

 in having a small rib at the bottom of the groove, and in being relatively shorter. 

 Pictet and Campiche state that the small rib is not always present. I have seen 

 no trace of such a rib in even the best preserved examples of L. gaultina. See also 

 Lima elongata (p. 36). 



Remarks. One of the specimens figured by Sowerby as Plagiostoma elongata 

 (the upper figure 2 of Plate DLIX) is probably an example of this species, but since 

 it is an internal cast only, it is difficult to be sure of its identity without seeing 

 other specimens from the same horizon. The specimen in question, however, 

 agrees in form and in the characters of the ribs with other internal casts which 

 undoubtedly belong to this species. D'Orbigny referred this species to Lima 

 parallela (Sowerby) and also included with it L. elongata, Sowerby (p. 34). 



Types. The specimen figured by Sowerby, mentioned above, is stated to come 

 from the " Greensand of Folkestone." D'Orbigny's specimens of Lima parallela, 

 d'Orbigny non Sowerby, came from the Gault of Gerodot and Dienville (Aube). 



Distribution. Gault of Folkestone (zones ii, vii, ix). Gault of Ventnor and 

 Black Ven. Cambridge Greensand (derived). Upper Greensand (zone of 

 Schlwnbachia rostrata) of Devizes. Internal casts from the Speeton Clay (zone of 

 Belemnites jaculum, C 11) seem to be indistinguishable from this species. 



LIMA (MANTELLUM) INTEELINEATA, Juices- Browne, 1877. Plate VI, figs, la, b. 



1877. LIMA INTERLINEATA, A. J. Jukes-Browne. Quart. Journ. Geol. Soc., 



vol. xxxiii, p. 502, pi. xxi, fig. 10. 



Description. Shell moderately convex, rounded-oblong. Umbones and ears 

 not seen. 



1 Measured perpendicular to the hinge-line. 



2 'Moll. Toss. Gres verts de Geneve ' (1852), p. 484, pi. xl, fig. 5 ; F. J. Pictet and G. Campiche, 

 'Foss. Terr. Crct. Ste. Croix ' (Mater. Pal. Suisse, ser. 5, 1869), p. 156, pi. clxvi, figs. 4, 5. 



