clxxx INFERIOR OOLITE AMMONITES. 



Distinction. — From Dum. radians, thinner whorls ; more acute, less carinate 

 periphery ; finer smaller costse. 



Localities and Strata. — Gloucestershire: Cam Down, near Dursley, Cephalopod 

 Bed, Dumortieria horizon. Foreign : France, Le Bernard (Vendee), Lias superieur 

 (submitted by Mr. Chartron). 



Date of Existence. — Dumortierise hemera. 



Gostate to Striate. 

 The costate stage is sometimes omitted altogether. 



20. Dumortieria diphyes, S. Buchman. Plate XLIII, figs. 5, 6 (Type), fig. 7. 



Plate XLII, figs. 13, 14. 



1891. Dumortieria radiosa, This Monogr., PI. xlii, figs. 13, 14; PI. xliii, figs. 

 5—7. 



Description — Subplatyleptogyral, latumbilicate ; costate declining to striate; 

 periphery convexifastigate, parcicarinate. 



Distinction. — From Am. radiosiis, v. Seebach. Mr. E. Mascke, Assistant at 

 Gottingen Museum, who is making a special study of Inferior Oolite Ammonites, 

 has very kindly compared my figures with Seebach's original specimen, which is in 

 that collection. He writes : " The identification of Dumortieria radiosa appears to 

 me not to agree, for there is a whole series of differences." l He gives a table of 

 comparative measurements which show that Seebach's shell has stouter whorls and 

 a smaller umbilicus. 



21. Dumortieria inclusa, S. Buchman. Plate XLV, figs. 13, 14. 



1891. Dumortieria radiosa, var. gundershofensis, This Monogr., p. 254 

 (pars) ; 1892, PI. xlv, figs. 13, 14. 



Description. — Platysubleptogyral ; subangustumbilicate ; spissicostate to striate 

 to spissiparvicostate ; periphery subtabulate, carinate. 



Distinction. — From D. radiosa, var. gundershofensis, the umbilicus being costate 

 and not showing the tendency to expand noticeable in Haug's figure. 



22. Dumortieria sp. Plate XLII, figs. 1, 2. 



1891. Dumortieria radians, This Monogr., PI. xlii, figs. 1, 2. 

 1 In lift., August 29th, 1902. 



