Fish-remains from the Parana Formation. 3 



the family Trygonidaj, as already observed by Jaekel*. 

 There are two typical examples in the National Museum, 

 Buenos Aires. 



3. Myliobatis americanus, Bravard. 



1858. Myliobates americanus, A. Bravard, Monogr. Terr. Marinos Terc. 



Parana, p. 53. 

 1896. Myliobates americanus, G. de Alessandri, Atti R. Accad. Sci. 



Torino, vol. xxxi. p. 724, pi. i. fig. G. 



The best-known specimen is described and figured by 

 Alessandri, but this is too imperfect for specific determination. 

 It seems probable that some of the detached teeth labelled as 

 belonging to this species are truly referable to Rhinoptera. 



4. Gestracion paranensis (Alessandri). 



1896. Acrodus paranensis, G. de Alessandri, he. cit. p. 723, pl.i. fig. 5. 



There are two teeth of this species in the ISan Paulo 

 Museum. On careful comparison with Gestracion they are 

 found to agree exactly with the larger grinding-teeth in this 

 existing genus. There is therefore no justification for 

 referring them to the extinct Mesozoic genus Acrodus. 



5. Odontaspis elegans (Agassiz). (PI. T. figs. 1-5.) 



1843. Lamna eleyans, L. Agassiz, Poiss. Fo»s. vol. iii. p. 369, pi. xl. b, 

 fig. 24 (non p. 289, pi. xxxv. figs. 1-7, pi. xxxvii. a, figs. 58, 59). 



1858. Lamna eleyans, A. Bravard, op. cit. p. 52. 



1858. Lamna unicuspidens, A. Bravard, op. cit. p. 52. 



1885, Lamna eleyatis, F. Noetling, Abh. Geol. Specialk. Preussen u. 

 Thiiring. Staaten, vol. vi. pt. 3, p. 61, pi. iv. 



1896. Odontaspis eleyans, G. de Alessandri, he. cit. p. 720, pi. i. fig. 1. 



1896. Odontasjns Hopei, G. de Alessandri, he. cit. p. 720, pi. i. fig. 2. 



1899. Odontaspis eleyans, A. S. Woodward, Proc. Geol. Assoc, vol. xvi. 

 p. 8, pi. i. figs. 15-18. 



All the teeth from Parana referred to this species are rather 

 small, and five well-preserved specimens are represented in 

 PI. I. figs. 1-5. It seems impossible to distinguish them 

 from the typical teeth of 0. elegans from the European Eocene, 

 but the striation of their inner face is perhaps more feebly 

 marked than in the latter. Most of the specimens are much 

 rolled and abraded. When their inner face is worn quite 

 smooth they are of the form referred to 0. Hopei, Ag\, by 

 Alessandri ; when they have lost their lateral denticles they 

 are the Lamna unicuspidens of Bravard, as shown by his 

 label in the British Museum. 



* O. Jaekel, ' Die Focaenen Selacliier vom Monte Bolca ' (1894), p. 140. 



1* 



