20 TYPE AMMONITES— III 1920 



the furcation point VIA Ribs are strong, sharp, compressed, 

 (laminar), rising very slightly ruricostate from inner edge, continuing 

 thus to V, then bending forwards, fairly regularly bifurcate, on a 

 sweeping curve to middle of periphery : guide-line from this cuts through 

 next forward primary. Umbilicus somewhat cadiconic without definite 

 inner margin. End of whorl shows complete mouth-border — quite 

 plain, curving to a long, forwardly projected, somewhat incurving 

 rostrum which is carinate (cf. Cardioceras cordatum ; Loriol, Pal. 

 Suisse, XXIX, n, 7). Carina presumably formed on last four or five 

 ribs (but periphery damaged) : same distance of terminal part shows 

 decay of ribbing and contraction of cone. Body-chamber £ of whorl. 



Weymouth, Dorset, " Oxford Clay " — a bluish calcareous matrix — 

 [junction of " Oxford Clay " with Lower Calcareous Grit, pre-vertebrale, 

 Argovian, about intermediate 4, 5] ; Mus. Geol. Surv. England, 30371 ; 

 S. 51, 43, 63 (57), 31.5 ; 68, 43, 53 (45), 30 ; max. c. 79 mm., Holotype 

 and Genotype. 



Weissermeliceras, g. n. Genoholotype, W. longilobatum, n. 

 (PL CLXXXIII). Swelling serpenticone ; periphery 2 to 1 c ; ornament 

 4, rather small, regular, mostly bifurcate, occasionally intercalate, 

 VL 2 , little difference in size between primary and secondary ribs, 

 the former versiradiate, the latter prorsiradiate, making a wide V on 

 periphery. Suture-line with particularly long and slender lobes, L l well 

 below guide-line, L 3 just below, aux. 3 touching. 



Like Eboraciceras, but distinguished by the finer, more regular 

 ribbing and the long slender lobes. 



England (Yorkshire) ; East Prussia ? 



W. longilobatum, n. (PI. CLXXXIII). Cf. Quenstedticeras 

 sutherlandice ; Weissermel, non Murchison sp. (Zeitschr. Deutsch. geol. 

 Ges. XL VII, 1895, xi, 3 only). The genotype is a specimen sent from 

 Sedgwick Museum, Cambridge, with name Quenstedticeras ordinarium, 

 but it is well distinguished from that species. It agrees with Weissermel's 

 figure, except that he shows more curvature of primary ribs and somewhat 

 more spaced ribbing towards end of whorl. From iron-stained sandstone 

 of so-called Kelloway Rock, Scarborough ; Callovian, athleta ; S. 53, 

 43-5- 45» 2 6-5 ; size of specimen 63 mm. ; max. c. 84 ; 28 ribs on whorl 

 to 53 mm. diam. 



Eichwaldiceras, g. n. Genoholotype, Ammonites carinatus, 

 Eichwald, (Lethaea rossica II, 1868, xxxiv, 8). Serpenticone, rapidly 

 developing cadicone ; periphery, 1 ; ornament, 4 ; costs rursiradiate, 

 bifurcate from swellings on edge of inner margin. 



The serpenticone stage belongs to brephomorphs [and anamorphs], 

 which also show an attempt towards carination : this only achieves 

 a sequence of V-costae, and is soon lost — swollen stage rapidly develops 

 with a broadly-rounded periphery. A very inflated cadicone is developed, 

 much like Cadoceras ; but the genus is distinguished by the more distinct 

 attempt towards carination in early stages, by developing a cadicone 

 out of a serpenticone without passing through a platycone stage. 



The species figured by Weissermel (Cadoceras carinatum; Quenstedic. ; 

 Zeit. Deutsch. Geol. Ges., XLVII, 1895, xn, 1) and by R. Douville, 

 (Quenst. carinatum ; Cardioc. ; 1912, x (iv), 57, 58, non caet.) are 

 presumably the cadiconic developments of Eichwald 's species, that is 

 later developments, biologically, of Eichwaldiceras, and require new 

 names. . 



Sufficient genera of Cadoceratidse have now been described to 

 illustrate the method of work, but not sufficient to deal properly with 



