CRANIAL OSTEOLOGY OF XllJi: OSTEOGLOSSID.L. 271 



traverse tliis statement, but I suspect that the " superior 

 pharyngeal " bone stated to be present in Osteoglossum and not 

 in Seterotis is the dentigerous plate that underlies the car- 

 tilaginous fourth pharyngobranchial. 



The deductions that one draws from the above summary are 

 that, so far as craniological characters indicate, the three genera 

 are closely allied, that Arapaiina is the most primitive of the- 

 three, and that there is a closer affinity between Osteoglossum and 

 Arapaima than between Seferotis and either of these forms. It 

 would be of great interest to ascertain whether such of the 

 above characters as are common to Arapaima, Osteoglossum, and 

 Seterotis, more particularly the entopterygo-parasphenoidal 

 articulation, are possessed by the skulls of the extinct Dapedo- 

 glossus of the freshwater Eocene of Wyoming, and Brycluetus 

 of the marine Eocene (London Clay) of Sheppey, which genera 

 are included in the family Osteoglossidse. I have made an 

 inspection of the remains of these fishes in the G-eological 

 Department of the British Museum, only to find that the parts 

 most interesting in the present connection are either broken 

 away or are concealed by matrix. 



Taxonomic Position of the OsTEOGLOssiDiE. 



Valenciennes (Hist. Nat. Poiss. vol. xix. 1846) placed Osteo- 

 glossum with Syodon, following immediately after the Mormy- 

 roids, which he said they resembled in the structure of their 

 alimentary canal (p. 287). Arapaima and Heterotis he discussed 

 in consecutive chapters, and the former he regarded as ciosel}^ 

 allied to Amia (p. 439). Johannes Miiller (" Ban und Grrenzen 

 der G-anoiden," Abhandl. Akad. Wiss. Berl. 1844, p. 190) placed 

 the three genera Arapaima, Osteoglossum, and Seterotis together 

 at the end of his " Clupeidse," a very large family including not 

 only those fishes which we are now accustomed to regard as 

 " Clupeoid," but also such forms as Notopterus, Amia, Alepo- 

 cephalus, Elops, and Stomias. 



Giinther (Brit. Mus. Cat. Pishes, vii. 1868, p. 377) founded a 

 special family, the Osteoglossidse, to include the genera Osteo- 

 glossmn, Arapaima, and Seterotis, and the family has been 

 adopted without alteration in all subsequent schemes of classifi- 

 cation, except an admittedly artificial scheme of Cope's (Trans. 

 Amer. Phil. Soc. n. s. xiv. 1871, p. 455), in which the Heterotidse 

 are associated with the Galaxiidse, and separated from the 



