xii YORKSHIRE TYPE AMMONITES— II Apr 



1918 



in a wide sense as type. Stepheoceras only replaces Stephanoceras in 

 regard to the Humphriesianum-group. It is quite incorrect to take as 

 type of my genus a species not only not referred to in the description, 

 but actually excluded by me from my genus ; for the species is particularly 

 placed by me as a Cceloceras, — " C. coronatum," p. 454. 



Result 

 Genus, Stepheoceras, S. Buckman, 1898 ; Genosyntypes Stepheoc. 

 humphriesianum Sow. in general ; Genolectotype, "Am. Humphriesi[anus] 

 Sow.,"[=J. de C. Sowerby, Min. Conch., Sept. 1825, PI. d, f.i, large 

 specimen], Mascke, 1907, p. 34. 



Genus, CHAMOUSSETIA, R. Douville 



1912, Cardioceratides ; Mem. Soc. Geol. France, xix (2), p. ig. 



" Type du Genre : Ammonites Chamousseti d'Orb., d'Orbigny : 

 Paleontologie francaise, terrains oolitiques ou jurassiques, p. 437-438, 

 pi. 155; 1847." 



D'Orbigny wrote A. Chamusseti ; but Douville says " dediee an 

 geologue savoisien Chamousset," and so the alteration is justified. 



Genus, LYTOCERAS, Suess 



1865, Ueber Amm.; Sitz. Nat.-Wiss. CI. Wiener Akad. lii, 78. 



" Lytoceras (Xvros, gelost) . . . Als den Typus dieser Gattung 

 sehe ich Lyt. fimbriatum Sow. an " 



It may be doubted if Suess correctly identified Sowerby 's species 

 any more than other authors have. Zieten and Hauer went far astray. 

 D'Orbigny was reasonably near, so was Wright, while Pompeckj (Rev. 

 Amm. Schwab. II, 1896, p. 112) and S. Buckman (Q.J.G.S., LXI, 1905, 

 p. 143) both accepted the figures of d'Orbigny and Wright as representing 

 Sowerby's species. All this is wrong. Even Vadasz (Jurasch. Bakony, 

 Wiss. Erforsch. Balatonsees I (1) 1910, p. 73) who gives d'Orbigny's and 

 Wright's figures as synonyms of Lytoc. postfimbriatum, Prinz-Vadasz, 

 failed to note the real difference. No figures in literature yet given 

 agree with the form delineated by Sowerby, so far as I am aware : I 

 have seen his type. All these errors show that Suess can hardly have 

 succeeded where others failed. It is reasonable, then, to take the figures 

 of Am. fimbriatus in existence at the time he wrote as genosyntypes of 

 his genus and from these to select Am. fimbriatus, d'Orbigny, as geno- 

 lectotype since it is the nearest to Sowerby's, though doubtfully even 

 congeneric. This follows Wright who gave, as the typical species of 

 Lytoceras, a woodcut of d'Orbigny's figure (Mon. Lias Amm. 1880, p. 243, 

 1883, p. 406). 



Result 

 Genus Lytoceras, Suess 1865 > Genotype, Lytoceras fimbriatum (Sow.) 

 Suess- A tn. fimbriatus Sowerby, Zieten, Hauer, d'Orbigny, etc, genosyn- 

 ies. Genolectotype, Am. fimbriatus, d'Orbigny, Pal. franc. Terr. Jur., 

 1S45, PI. xcvni,= , teste Vadasz, loc. tit., Lytoc. postfimbriatum, Prinz- 

 Vadasz ; but it is doubtful if Wright's species is the same as d'Orbigny's 

 and if cither is the same as the L. postfimbriatum figured by Vadasz in 

 P- 74. 



