nob YORKSHIRE TYPE AMMONITES— II Apr. 



no. AMMONITES ELEGANS, Young & Bird 

 (Plate CX) 



Original Description 

 [Young & Bird, 1822, pp. 251, 327.] 



" [P. 251]. No. 7, PL xiii, corresponds with the a. elegans of 

 Sowerby, Tab. 94, Fig. 1 ; having the same form, the same sigmoidal ribs, 

 sharp keel, and truncated internal angles. It is not uncommon in the 

 lias nodules. The specimen figured is small, but singular, having portions 

 of the chambers hollow, containing when discovered a considerable 

 quantity of oil. 



"[P. 327]. Plate xiii. . . . Fig. 7. Ammonites elegans. 

 Alum shale." 



Additional Details 



Young & Bird, 1828, pp. 267,359. " No. n, PL xiii, is another 

 of this family [ammonites with sigmoidal ribs], corresponding with 

 Sowerby's A. elegans, Tab. 94. 1. It is thin, slender ribbed, and has 

 the inner angle of the whirl truncated, the truncated part generally 

 forming a concave surface, like the groove in A. angulatus [Sowerby]. 



" [P- 359]- Plate xiii. . . . Fig. n [7] 1 A. elegans. Lias 

 bands." 



Remarks 



The Yorkshire species is generically different from A. elegans, 

 J. Sowerby, June, 1815. A topotype is now illustrated to which the 

 name Eleganticeras pseudo-elegans has been applied (Y.T.A. II, 191 3, 

 p. viii). To this specimen, the genotype and holotype, the following 

 description applies : — 



Proportions, 89, 42, 22, 26 ; Platy-, subleptogyral, sublatumbilicate. 



Stages, conch, platycone ; periphery, 3c ; ornament, 3c,2c, — striate 

 over and between obscure distant undulate subfalciform ribs, passing 

 to striate only : the ribs where present about of equal strength across 

 flat of whorl. Carina sharp, defined, septate ; umbilicus subexcentric with 

 sharply-defined concave margin. Suture-lines approximate — loculi quite 

 short ; accessory lobe in external saddle large, about equal to L2. Mouth- 

 border, plain curve similar to rib contour. 



Geological position, Jet Rock. 



Result 

 Eleganticeras pseudo-elegans, S. Buckman, 1913 (Am. elegans, 

 Young & Bird, non Sowerby), Whitbian, exaratum zone, Whitby, 

 Yorkshire. 



'See Am. clevelandicus, p. 109b. 



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