iogb YORKSHIRE TYPE AMMONITES— II Apr. 



109. AMMONITES CLEVELANDICUS, Young & Bird 



(Plate CIX) 



Original Description 

 [Young & Bird, 1822, pp. 253, 327.] 



" [P. 253]. No. ii, PI. xiii, is another small, beautiful, and rare- 

 ammonite, from the beds corresponding with the Staiths band in the 

 front of Cranimoor. It resembles a. Maltonensis, both in its shape and 

 its markings ; but its ribs are waved, and are less prominent, and extend 

 across the whirl to near the crenulated keel, where they bifurcate. We 

 may name this shell a. Clevelandicus." 



" [P. 327]. Plate xiii . . . Fig. 11. Ammonites Cleveland kits. 

 Alum Shale. 



Additional Details 



Young & Bird, 1828, pp. 267, 268, 359. " Of the thin discoid 

 ammonites, with sharp keels, generally crenated, we have several species. — 

 No. 7, PL xiii, from the hard bands of the Hawkser shore, corresponds 

 with Sowerby's A. excavatus, Tab. 105. The keel, or thin edge, is crenated, 

 the aperture is sagittate, and the inner edge of each whirl nearly perpendi- 

 cular, and rather deep. The sides are marked with faint sigmoidal ribs, 

 which in the young specimens, or interior whirls, are partly fimbriated. 

 In our First Edition, we figured a small specimen under the name 

 A. Clevelandicus. This last name may now be transferred to a small 

 species in the same beds, which Mr. Sowerby seems to mistake for the 

 young of A. excavatus. It has a smaller aperture, the outer [p. 268] 

 whirl being not quite so broad ; and the central part is not deeply sunk, 

 as in A. excavatus, in which the interior whirls rapidly diminish in 

 thickness." 



" [P- 359] Plate xiii. . . . Fig. 7. [11]. A. Cleveland icus, 

 (excavatus, Sowerby.) Lias bands." 



Remarks 



Proportions 118, 46, 18, 24 : Perplaty-, subleptogyral, suban- 

 gustumbilicate. 



Stages, conch, oxycone ; periphery, 2c ; ornament, 4c. Rib con- 

 tinuously strong to undefined periphery, with short ribs intercalated 

 on outer lateral border. 



The specimen now illustrated (PL CIX) is not the holotype of 1822 

 but the heautotype of the description of 1828. There is, however, obviously 

 a mistake in the explanation of Young & Bird's PL xiii (1828) : Fig. 11 

 is Am. clevelandicus and not Am. elegans, while Fig. 7 is Am. elegans to 

 which the artist has, by confusing the specimens he had represented, 

 given the keel details of Am. clevelandicus. Thus Fig. 11 (PL xiii) of 

 1828 is practically the same as Fig. 11, 1822 ; and illustrates the holotype 

 of A. clevelandicus ; but Fig. 7 of 1828 represents some details of the 

 heautotype of A . clevelandicus grafted on a drawing of A . elegans : it is 

 a synthetograph. 



Genus Amaltheus ; Family Amaltheidce. The species, however, differs 

 from other similar-shaped Amalthei by the feeble projection of the 

 radii on the periphery, the consequent lack of rostration, and by the 

 obscureness of depressed areas parting periphery from sides. Thus the 

 intercalated radii which make up the crenulations of the periphery are 

 not confined to the indefinite keel but begin on the sides, 



