EASTMAN: DESCiarTIONS OF BOLCA FISHES. 27 



Altogether seventeen species of elasmobranchs are known from the Monte 

 Bolca horizon, a list of which is subjoined : 



Speciks of Elasmobranchs from Monte Bolca. 



1. Rhinohatis zignii (Heckel). 10. Promyliohatis gazolae (Zigno). 



2. " primuevus Zigno. 11. Lamna vincenti Winkler. 



3. Platijrhina holcensis (Heckel). 12. Odontaspis hopei Ag. 



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



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



6. Narcine molini i-Aktk.ii\. 15. Alopiopsis plejodon Lioy. 



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



8. " zignii (Molin). 17. Mesiteia emiliae Kramb. 



9. Urulophus crassicaudatus (Blv.). 



TELEOSTOMI. 



ACTINOPTERYGH. 



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 

 series 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 XLVTI. 



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, Poiss. Fuss., v. pt. 2, p. 126. 



1874. Platinx gigas A. de Zigno, Catalogo ragionato dei 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 



