Fish-remains fi'inn the Parana Form ifiui. 3 



the family Tiygonidti;, as alromly observed by Juckt-l *. 

 There are two ty|)ical examples in the National Museum, 

 Buenos Aires. 



3. Mi/liobatis americanuSj Brjivard. 



1858. M tfliolfates americamis, A. Bnivard, Monogr. Terr. Mariiios Turc. 



Parana, p. M. 

 18t)G. Myliuhates ainericatms, O. de Alessandri, Atti \i. .Vccad. Sri. 



Torino, vol. x.\.\i. p. 7i'4, pi. i. fig. 0. 



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 reterable to Rhinoptera. 



4. Cestracion paranensis (Alessandri). 



1896. AcrodvLS paraiieiisU, G. de Alessandri, loc. cit. p. 723, pl.i. fig. o. 



There are two teeth of this species in the tSan Paulo 

 Museum. On careful comparison with Cestracion 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 {Agass'\z). (PI. I. figss. 1-5.) 



1843. Lamna ele(/an.o, I>. Apassi/, Poiss. Fa».s. vol. iii. p. 3(39, pi. xl. i, 

 fi(j. 24 (^non p. 2^9, pi. x.\.\v. figs. 1-7, pi. xxxvii. a, figs. 58, 59). 



186b. Lamna elegans, A. Bravard, op. cit. p. 52. 



1858. Lamna unicn.<pide>is, A. |{ra\ard, op. cit. p. 52. 



1886. Lamna elci/anK, F. Noetliiig, Abh. Geol. Specialk. Preu.ssen u. 

 Thiirinp. Staaten. vol. vi. pt. .'{, p. 61, pi. iv. 



1896. Odoiifaspis elegant, G. de Ale.-8:indri, lor. cit. )>. 720, pi. i. fig. ]. 



1896. Odontasjn'if Jlopei, G. de Alessandri, loc. cit. p. 720, ]>!. i. tig. 2. 



1899. Odontaapin c/r(/a}ij>, A. S. Woodward, Proc. Geol. .Assoc, vol. \vi. 

 p. 8, pi. i. Hgs. 15^18. 



All the teeth from Parana referred to this species are rather 

 small, and five well-preserved specimens are represented in 

 PI. 1. figs. 1-5. It seems impos.'^ible 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 tiie latter. j\Iost of the specimens are much 

 rolled and abraded. When their inner face is worn quite 

 smooth they are of the form referred to O. IJo/iei, 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 Mu.seum. 



• U Jaek.l. ' I lie I'.ocaeneii ."-J.-lnrhier voni .Moiit«.> Bolca ' (1894). p. 140. 



1* 



