EASTMAN : DESCniPTIONS OF BOLCA FISHES. 27 



Altogether seventeen species of elasmobranchs are known from the Monte 

 Bolca horizon, a list of which is subjoined : 



Species of Elasmobranchs from Monte Bolca. 



1. Rhinobatis zignii (Heckel). 10. Promyliobatis gazolae (Zigno). 



2. " primaev us Zigno. 11. Lamtia vincenti Winkler. 



3. Platyrhina bolcensis (Heckel). 12. Odontaspis hopei Ag. 



4. " egertoni Zigno. 13. Carcharodon auriculatus (Blv.). 



5. " gigantea (Blv.). 14. Pseudogaleus voltai .Taekel. 



6. Narcine molini J aekel. 15. Alopiopsis plejodo7i\AoY. 



7. Trygon muricatus (Volta). 16. Carcharias (Scoliodoii) cuvieri (Ag.). 



8. " zig^iii (Molin). 17. Mesiteia emiliae Kramb. 



9. Urolophus crassicaudatus (Blv.). 



TELEOSTOMT. 



ACTINOPTERYGII. 



ALBULIDAE. 



MONOPTERUS Volta. 



Trunk elongated oval and laterally compressed. Head relatively short, with 

 steep frontal profile ; opercular bones well developed. Vertebrae at least 60 

 in number, half of them being caudal. Length of anterior pectoral fin-ray 

 exceeding maximum depth of trunk ; pelvic fins minute, situated nearer the 

 anal than the pectoral pair. Anal placed opposite the dorsal, and rising into 

 an acuminate lobe in front. Caudal very deeply forked, with a scaly lamella 

 extending over the middle of the tail at the base. Mouth opening small, a 

 sei'ies of conical teeth present along the margin of the jaws, and a series of 

 hemispherical crushing teeth placed further back. 



Monopterus gigas Volta. 



1796. Monopteros gigas G. S. Volta, Ittiolit. Veronese, p. 191, Plate XLVII. 



1818. Monopteros gigas H. D. de Blainville, Nouv. Diet. d'Hist. Nat., xxvii. p. 357. 



1835. Platinx gigas L. Agassiz, Neues Jalirb., p. 304. 



1838-44. Platinx gigas L. Agassiz, I'oiss. Foss., v. pt. 2, p. 126. 



1874. Platinx gigas A. de Zigno, Catalogo ragionato del Pesci Fossili, p. 151. 



The removal of this species from the genus Platinx, and its transfer to the 

 vicinity of Chanos, amongst the Albulidae, appears warranted by the presence 

 of numerous hemispherical crushing teeth in the pharyngeal region, and by the 



