UPPER, OR FLINTY CHALK. SOI 



probability, were originally cylindrical, but are now laterally compressed. 

 The aperture has its inner edge indented by the preceding whorl. The 

 back is smooth. The protuberances are indistinct, and wholly wanting 

 in some examples. 



This, and the species last described, are the largest ammonites of 

 the chalk formation * ; both are nearly destitute of ornament, yet their 

 forms are so dissimilar, that even fragments can be distinguished with 

 facility : those of A. Leivesiensis being flat, and thin, in proportion to 

 their magnitude; while the remains of A. peramplus are convex, and 

 almost cylindrical. 



Localities. Upper chalk, near Lewes, and Eastbourne. 



61. Belemnite . Tab. xvi. fig. 1. 



This figure represents the only species of belemnite, that occurs in 

 the Upper, and Lower chalk, of Sussex. 



It is smooth, cylindrical, and unUke most of the genus, has no external 

 sulcus. Longitudinal sections shew that a small tube extends from the 

 alveolus to the apex of the spathose part. 



LocaUties. Brighton, and Lewes. 



62. Scaphites striatus. {Grey Marl Fossils, No. 35.) 



This species has been discovered in the Lower chalk, at Brighton. 



63. Hamites alternatus. {Grey Marl Fossils, No. 39.) 



The existence of Hamites, in the Upper chalk, has not previously been 

 noticed : two decided examples of the present species have been found 

 near Lewes. 



64. Pecten quinquecostata. Tab. xxvi. figs. 14, 19, 20. 

 Subtriangular, slightly oblique, longitudinally costated, transversely 



striated ; lower valve gibbous, beaked, pentangular ; upper valve flat, front 

 pentarcuate, sides forming an acute angle ; margin crenulated ; ears 

 small. 



* A fragment of A. peramplus, sent some years since to Mr. Sowerby, must have belonged 

 to a specimen nearly three feet in diameter. 



