284 



CRETACEOUS LAMELLIBRANCHIA. 



sliire and "West Norfolk ; and by Rowe from the zone of Holader planus of Dover 

 and tlic Sussex coast, and from the zone of Micrasfer cor-testudinariinn of Dover. 



Fia. 3a 



Fig. 40. 



Fia. 39. — luoccramns lahiatus var hitiis, Sow. Zone of Holasfer planus, Swaffhani, Norfolk. Norwich 



Miiseum, No. 3296. Eiglit valve and anterior view. Natural size. 



Fig. 40." — Inoccramus lahiatus var. latns. Sow. One of the types of Inocerainus latv,s, Sowerby, 'Min. Conch.,' 



vol. vi, p. liJO, pi. dlxxxii, fig. 1 (lower figure). Swafl'liani. British Museum, No. 432G6. Natural size. 



Inoceeamus l.\biatus var. latus, Sowerby, 1828. Text-figs. 38 — 40. 



1828. Inoceeamus latus, J. de C. Soicerhij. Miu. Conch., vol. vi, p. 159, pi. 



dlxxxii, fig. 1. (Nou /. laitts, 

 Man tell). 



1854. — — J. Morris. Cat. Brit. Foss., ed. 2, p. 170 (partim). 



Remarl-s. — This variety differs from I. lahiatus in the much greater length of 

 the hinge-line in proportion to the height of the shell, in the greater convexity of 

 the anterior margin, the smaller convexity of the ventral margin, and the less 

 oblique form of the shell. On account of the greater length of the hinge-line the 

 curvature of the ribs and growth-lines is broader than in I. lahiatus. 



This variety appears to be confined to the zone of Holaster jilaitits, and is 

 common in the neighbourhood of Swaifham, Norfolk. The larger specimens which 

 I have seen are not sufficiently perfect for figuring, but a characteristic example 

 is figured by Sowerby. 



Types. — From the zone of Holaster planus of Swaffham. The smaller specimen 

 figured by Sowerby is in the British Museum (Fig. 40), but the larger specimen 

 cannot be found. 



Dlsfrihntiuv. — Zone of Holaster planus of Purley Junction Station, Surrey, and 

 Swaffham, Norfolk. 



