366 MR C. TATE REGAN ON THE 



Gymnodraco acuticeps. 

 Bouleng., I.e., pi. xvii. ; Pappenheim, Deutsche Sudpolar-Exped., xiii., Zool, v. p. 176, pi. ix. tig. 4 (1912). 



Depth of body 8 in the length, length of head about 3. Snout as long as post- 

 orbital part of head. Diameter of eye 5 to 6 in length of head, interorbital width 6 to 

 7. Lower jaw strongly projecting ; maxillary extending to below anterior margin of 

 eye ; gill-rakers short, sometimes almost vestigial except near the angle. Dorsal 28-30. 

 Anal 24-26. Pectoral truncated, | as long as head. Caudal truncate. Large dark 

 spots on head and body ; fins dusky. 



Victoria Land ; Wilhelm Land. 



Here described from the types, 200 to 300 mm. in total length, from Cape Adare, 

 4 to 8 fathoms. 



Family 4. CH.ENICHTHYID.E. 



This family differs externally from the Nototheniidse in the naked body, produced 

 spatulate snout, and non-protractile mouth. The skeleton of Champsocephalus esox 

 shows several peculiarities. The skull is depressed, with the long rostral lamina formed 

 by the frontals and the ethmo-vomer ; the parasphenoid meets the frontals between the 

 small lateral ethmoids at the anterior margin of the orbit. The palatine is represented 

 by the maxillary process, attached to the lateral edge of the rostral lamina near its 

 anterior end, and by a posterior portion articulating with the lateral ethmoid, these 

 being connected by a long and slender ligament ; the pterygoid is slender, and there 

 is no mesopterygoid. The prseorbital is large, but the suborbitals are unossified. The 

 pectoral arch is as in Notothenia. There are 57 vertebrae (28 + 29) ; the epipleurals 

 are sessile, but the ribs are not ossified. 



I have ascertained that Chtenichthys and Pagetopsis are essentially similar in the 

 structure of the rostrum, the palato-pterygoids and the pectoral arch, and in the 

 absence of ribs. In all the genera the mouth is very distensible and the dentaries 

 are freely movable on the articulars ; this is the case, to a certain extent, in the 

 Bathydraconidse also. 



Synopsis of the Genera. 



I. Two lateral lines ; pelvic fin-rays all branched or bifid, the middle ones the longest. 



A. Lateral line without bony plates ; a spinous dorsal fin, subcontinuous 



with the soft dorsal. 

 No spine on snout ; spinous dorsal of 9 or 10 spines, not more than ^ the length 



of soft dorsal . . . . . . .1. Champsocephalus. 



A median spine near end of snout ; spinous dorsal of 12 to 15 spines, more than 



\ as long as soft dorsal ...... 2. Pagetopsis. 



B. Lateral line with bony plates. 



A spinous dorsal fin ........ 3. Chienichthys. 



No spinous dorsal fin 4. Parachxnichthys. 



(ROY. soc. EDIN. TKANS., VOL. XLIX., 284.) 



