Q. C. Crick — On Tniaegoceras. 127 



VI. — Note on the genus TMAEGoasRASf Hyatt. 

 By G. C. Crick, F.G.S., of the British Museum (Natural History). 



IN a recent number of the " Neues Jahrbncli" (1901, Bd. ii, Heft 3, 

 pp. 158-170, 6 text illust.) Dr. J. F. Pompeckj, of Munich, has 

 an interesting paper on the genus Tmaegoceras. The genus was 

 established by Hyatt ^ in 1889 for the two very rare Ammonites 

 from the Lower Lias of the Alps, Ammonites latesulcatus, F. v. Hauer,^ 

 and Arietites levis, G. Geyer.^ To these, in 1899, G. Bonarelli* 

 added a third species, Tmaegoceras Paronai, from the Lower Lias 

 of the Central Apennines, at the same time assigning to this genus 

 Schafhautl's Ammonites Melli.^ But as Mojsisovics ® pointed out in 

 1893, Schafhautl's species is a Tropites, whilst Ammonites latesculcatus, 



F. V. Hauer, Arietites levis, G. Geyer, and Tmaegoceras Paronai, 



G. Bonarelli, have nothing whatever to do with that genus. Of 

 these three species Dr. Pompeckj regards Ammonites latesulcatus, 

 F. V. Hauer, and Tmaegoceras Paronai, G. Bonarelli, as generically 

 identical, and with them he unites also Quenstedt's Ammonites 

 dorsosulcafas'' and his own new species (T. crassiceps^), which he 

 describes from the Lower Lias (zone of Arietites Bucklandi) in the 

 neighbourhood of Tubingen (Wlirttemberg). He considers Arietites 

 levis, G. Geyer, to be a true Arietite, probably related to Arietites 

 ophioides (d'Orb.), Wahner,' or Arietites Cordieri, Canavari. ^" 



As emended by Pompeckj the genus includes the four following 

 species : — 



1. Tmaegoceras latesulcatum, F. v. Hauer, sp. Lower Lias : Adneth, 



Bischofsteinbruch (Nordostalpen). 



2. Tmaegoceras dorsosidcatiim, F. A. Quenstedt, sp. Upper boundary 



of the Zone of Schlotheimia angulata : Vaihingen, near 

 Stuttgart (Wlirttemberg). 



1 A. Hyatt, " Genesis of the Arietidae" : Mem. Mus. Comp. Zool. Harvard Coll., 

 xvi, No. 3 (1889), p._,125. 



- F. V. Hauer, " Uber die Cephalopoden aus dem Lias der nordostlichen Alpen" : 

 Denkschr. Akad. Wissensch., Wien, Bd. xi (1856), p. 44, pi. ix, figs. 1-3. 



^ G. Geyer, "Uber die liasisohen Cephalopoden des Hierlatz bei Hallstatt": 

 Abhandl. d. k.k. geol. Eeichsanst., Wien, Bd. xii, No. 4 (1886), p. 252, pi. iii, 

 figs. lOa-c. 



* G. Bonarelli, " Cef alopodi Sinemuriani dell' Appeunino Centrale " : Palaeontogr. 

 ital., vol. V (1899), pp. 66-7, fig. 1. 



5 Schafhautl, " Geognostische Untersuchungen dessiidbayerischenAlpengebirges," 

 1851, p. 107, pi. XV, fig. 21. 



^ E. V. Mojsisovics, "Die Cephalopoden der HallstatterKalke " : Abhandl. d. k.k. 

 geol. Eeichsanst., Bd. vi, No. 2 (1893), pp. 201, 202, 207. 



■^ F. A. Quenstedt: " Die Ammoniten des Schwabischen Jura," p. 109, pi. xiii, 

 figs. 33-35 (1885). 



8 J. F. Pompeckj, " Ueber Tmaegoceras, Hyatt": Neues Jahrb., 1901, ii, 

 pp. 162-165, text-figs. \a-i. 



^ Fr. Wahner : " Beitrage zur Kenntniss der tieferen Zonen des unteren Lias der 

 nordostlichen Alpen" (Beitr. zur Pal. Osterr.-Ung., etc., Bd. vi, 1888), p. 164, 

 pi. XXV, fig. 5. 



1" Fr. Wahner: op. cit., vi (Beitr. zur Pal. Osterr.-Ung., etc., Bd. viii, Heft 4, 

 1891), p. 193, pi. ivii, figs. 1-4 ; pi. xviii, figs. 1-6. 



