AND OTHER ENGLISH NUMMTJLITES. 



139 



d'Archiac and Haime's Nummulites planulata, var. a, from Jette 

 Belgium ; but the latter has a biconvex centre (opake when mounted 

 in balsam), has narrower whorls (in the proportion of 1 to 4, instead 

 of 1| to -1), and grows to a somewhat larger size. To distinguish 

 our variety (which characterizes a well-marked geological zone), 1 

 propose to give it the name of Prestwichiana ; and, as the small 

 biconvex variety of N. planulata passes binomially as iV". variolaria, 

 so this small depressed variety of the same species may be allowed 

 to stand on a. similar footing, and be known as AT. Prestwichiana. 



" In the sandy clay-bed at Alum Bay the shells of this little 

 ISTummulite are very numerous, and often well preserved, but not 

 unfrequently much crushed by pressure. In many specimens, 

 especially large ones, the chambers are occupied by iron -pyrites ; 

 and neat casts may be obtained by carefully dissolving the shell in 

 weak dilute acid. In the clay at High Cliff the shells are not so 

 numerous, are very much compressed, and so highly pyritized that 

 they are readily destroyed by the atmosphere." 



It may be added that even in the smaller specimens the alar 

 chambers though " radiate " are not straight, but curved ; and in 

 the largest individuals they become "sinuate" ; therefore this form 

 is one of the " sinuo-radiates " *. 



1863. In a letter dated November 9, 1863, the Eev. 0. Fisher 

 wrote : — 



" This N. Prestwichiana seems to range over what I have taken 

 as the junction of the Bracklesham and Bartons. At Alum Bay the 

 forms with which it occurs are Barton forms, while at Hunting 

 Bridge it lies at the bottom of a thick bed of Bracklesham fossils." 

 He also refers to N. variolaria, a species of the Barton series, as 

 occurring at King"s-Garden Gutter, New Forest (" Brook," F. 

 Edwards), " rare, but persistent." 



1876. Ann. & Mag. Nat. Hist. ser. 4, vol. xvii. p. 286. Among 

 some fossil jSTummulites dredged up in the English Channel, N. 

 Prestwichiana was met with, and it is noted that this last form was 

 described in the Quart. Journ. Geol. Soc. vol. xviii. pp. 93, 94, as 

 N. planulata, var. Prestwichiana, and possibly may be essentially 

 the same as N. planulata, var. a. minor, d'A. & H., which occurs at 

 Jette, in Belgium." 



1878. Dixon's ' Geology of Sussex,' &c, 2nd edition by T. E. 

 Jones. 



Page 172. Nummulina variolaria (Lamarck). Strongly ribbed ; 

 pi. ix. (10), fig. 7. 



Page 172, note by T. E. J. : — 



" Nummulina elegans, Sow. <Min. Conch.' t. 538, referred to at 

 p. 85 in the First Edition, was [in part] originally described from a 

 specimen said to have come from a well f at Emsworth, near Ports- 

 mouth. It is not known anywhere else in England. The figured 

 specimen [11th figure in fig, 2 of the plate] closely resembles speci- 



* Ann. & Mag. 1ST. H. ser. 3, vol. v. p. 109, vol. viii. p. 115. 

 t I do not know where I learnt this fact ; perhaps Mr. Sowerby gave me 

 the information. 



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