Analytical Synoj)sis of the Order of Sqiiali. 387 



18, — Dr. Bleeker in his "Sjstematis Pisciura IsTaturalis Tenta- 

 men," retained tlie sharks as a sub-order {Squalini) of the order 

 of Plagiostomi, which formed the fourth order of fishes and the 

 first of the third legion or Elasmohranchii. Two orders were 

 embraced in the hxtter gi'oup, the Plagiostoini^ with the two 

 orders of Squalini and Rajini, and the Holocephali. 



The Squali were thus sub-divided : — 



Sectio I. Proktopterides. 

 Tribus I. Dinotopterini. 



FaMIUA 5. ScYLLIOIDEI=:ScYLLINI Bp. = ScYLLIA Mil. 



Gen. Scyllium MH., Thyellina Milnst. (foss.), Pristiurus Bp., 

 Chiloscylliura MH., Ginglymostoina MH., Stegostoma MH., 

 Scylliodus Ag. (foss.), an huj. loc ? 

 Familia 6. Carcl)aroidei = Carcb arise MH. = Carcbarid3e Ricbd. 

 Gen. Carcbarias MH., Leptocarias Smitb, Glyphis Ag., Triteno- 

 don MH. 

 Familia 7. Zygaenoidei = Zyganinae Swns.z^Zygajnidse Ricbd. 



Gen. Zygfena Cuv. = Spbyrna Raf. 

 Familia 8. Galeoidei = Galeid8e Ricbds. 



Disk and tail nearly equal. Head emarginated in front. Spira- 

 cles far behind eyes. Teeth transverse, with one point. Narcaciontin^. 

 Spiracles with dentated borders. ' Narcacion. 



Spiracles with smooth borders {Torpedo occidentalis St.). Tetronarce. 

 Disk and tail nearly equally long. Head entire or convex in front. 



Spiracles close behind eyes. Teeth rhombic or hexagonal. Narcinin.e. 

 Dorsals two. 



Ventrals united beneath the tail. Teeth rhombic, acute 



behind. Discopygce. 



Disk orbicular. Discopyge. 



Ventrals separated. Teeth rhombic, with a median point. Narcinm. 



Nasal viilve with single median lobe ; snout convex. Narcine. 



Nasal valve tri-lobed. 



Disk sub-circular {Narcine Tbnlei Henle). Cyclonarce. 



Disk pentagonal {Narcine Indica Henle). Gonionarce. 



Dorsal single. Teeth rhombic, each with a median point. Aatrapce. 



Disk sub-circular. Astrape. 



• Dorsal obsolete. Teeth hexagonal and flat. Tetnerce. 



Disk sub-circular. Temera. 



