THE AX>fALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[EIGHTH SERIES.] 

 No. 47. NOVEMBER 1911. 



LXV. — The Classification of the Teleostean Fishes of the 

 Order Ostariophy si, — 2. Siluroidea*. By C. Tate Rkgan, 

 M.A. 



(Published by permission of the Trustees of the Biiti?h Museum.) 



The Siluroids may be thus defined : — Ostaiiopliysi with the 

 body naked or covered with bony plates, tlie mouth uon- 

 protractile and the branchiostegal rays often numerous ; 

 parietals, symplectic, and suboperculum absent ; second, 

 third, and fourth vertebrae ankylosed to form a complex to 

 which the fifth is rigidly attached ; parapophyses ankylosed 

 "with centra ; epipleurals and epineurals absent. 



As in all Ostariophysi, there is no basisphenoid, but an 

 orbitosphenoid is always present ; the latter joins the frontals 

 above, the paraspbenoid below, the lateral ethmoids in front, 

 and the alisphenoids behind. There is no opisthotic, but 

 the other otic bones are present ; the epiotics are rarely 

 prominent, but in the Doradidse they are important elements 

 of the cranial roof. The praemaxillaries are typically fixed, 

 but in the Callichthyidse and Loricariidse they are movably 

 articulated with the mesethmoid ; sometimes the toothed 

 prsemaxillaries extend right back to the angle of the mouth 

 {Wallago, Ayeniosus, Asterophysus), and the posterior exten- 

 sion may segment o.ff as a distinct bone {Eutropiichthys) , 



* The Cyprinoidea have been dealt with in a separate paper, suprd, 

 p. 13. 



Ann. iSc Mag. N. Hist. Ser. 8. Vol. viii. 37 



