722 MR. c. TATE REGAN' ON [June 19, 



8. A Classification o£ the Selachian Fishes. 

 By C. Tate Eegan, B.A., F.Z.S. 



[Received May 29, 1906.] 



(Text-figures 115-124.) 



The classification of the Selachians which I propose is as 

 follows : — 



Subclass SELAGHII.* 



Series I. TREMATOPNEA.'f 

 Order 1. PLEUEOPTERYGII. 



Family 1. Gladoselachidce. 



Cladoselachiis. 

 Family 2. Cladodontidce. 



Cladodus, Symmorium.. 



Order 2. ACANTHODII. 



Family 1. Acanthoessidce. 



Acanthoessus, Chiracanthus. 

 Family 2. Diplacanthidce. 



Diplacanthus, Climatias, Ischnacanthus. 

 Order 3. ICHTHYOTOMI. 



Family 1. Pleuracanihidm. 



Pleuracanthus, Xenacanthus. 



Order 4. EUSELACHII.J 



Suborder 1. PLEUEOTEEMATA.§ 



Division 1. jSTotidanoidei, 



Famil}^ 1. Chlamydoselachidce. 



Chlamydoselachus. 

 Family 2, Hexcmchidce. 



Hexanchus, Heptranchias. 



* I use the word Selachii in the same sense as did Miiller in 1846 and as tlie 

 equivalent ot the feelaciens of Cuvier in 1817 (Regne Anim ii p 121) 



t The names Trematopnes and Chismopnes, the latter an obvious missnelUno- 

 proposed m 1806 by C. Dumeril with a wider 'sigmficance, may be LaTi^ Led and 

 applied to the two series of Selachians. = "^-^ "« i^atinisea and 



I The Petalodontida3 and Psammodontid&, comprising several genera from 

 Permian and Carboniterous strata, appear to pertain to this Order, but cannotZ 

 assigned a definite position. i^auiiui, ue 



§ The Pleurotremata and Hypotremata are equivalent to the Pleurotremes and 

 Hypotremes of C. Dumeril. 



