F.DIBLE FISHES OF QUEENSLAND.— OGILBY. 23 



its own shelter in sandy places where the substratum is sufficiently compact to 

 make successful tunneling possible. Jaws and gaping mouth are its only 

 entrenching tools, but meet its every need. It is found not uncommonly upon 

 the open reef in little colonies, the formation of which is probably due in part to 

 the discontinuous occurrence of suitable bottom rather than to the social instincts 

 of the fishes themselves. During the day, if undisturbed, Gnathypops may be 

 regularly observed resting nearly motionless in a semivertical position above its 

 burrow. When alarmed it retreats into its hole tail foremost and conceals itself 

 until the disturbance outside has ceased. Then it reappears cautiously, its beady 

 black eyee being so situated that it is able to sweep the horizon Avith minimum 

 exposure. If nothing happens to renew its alarm, it mounts a little farther until 

 its ventral fins are free, rests for a moment in the mouth of its burrow, and finally 

 rises easily and gracefully to its original position. Still another of these fishes 

 (as yet unidentified) shows a different variation of the tubiculous instinct. It 

 lives in holes, quite possibly worm-tubes, which it discovers ready formed in 

 pieces of dead coral upon the bottom, Its most striking structural feature is the 

 immense dorsal fin, which when raised seems nearly as high as the fish is long. 

 Its most interesting habit is that of protruding its body for about half its length 

 from the chamber it occupies, and then elevating and depressing its great fin 

 rapidly as if it were wigwagging in piscine code. This impression is heightened 

 when two individuals separated by no great distance stand erect and repeat the 

 performance in alternation. ' ' Nothing is known as to the breeding habits of these 

 fishes, nor have I ever seen an example with ripe spawn, though all those which 1 

 have handled were fully adult. That the young are never found along the fore- 

 shores nor in the debris of the seine net seems to demonstrate the demersal 

 character of the ova. No data are available as to their edible qualities, unless it 

 be that of an acquaintance, who took one home and had it fried ; he told me it 

 was "as good as any other rockfish. " On account of their scarcity and the 

 difficulty of obtaining them all the species are greatly in request for museum 

 collections, and every example should, therefore, be carefully preserved and 

 forwarded, with as little delay as possible, to the nearest scientific institution. Six 

 genera and thirty species are now recognized. As mentioned by Waite it has 

 been suggested in some quarters that Gnathypops may merely be the female of 

 Opistliognathus, but the fact that the latter genus is quite unknown in Australian 

 waters sufficiently contravenes any such theory. 



Appended is a key to the opisthognathoid genera. Those which are 

 printed in italics have not so far been found in Australian seas, but, with the 

 exception of the West Indian Lonchopisthus there is no insuperable reason why 

 the other genera should not occur here. 



a}. Maxillary about as long as the head, produced behind in a flexible lamina i. OpisthognathU'S" 

 a^. Maxillary much shorter than the head, but extending well beyond the eye, its distal extremity 

 truncate. 



*' Cuvier & Valenciennes, Hist. Nat. Poiss., xi, 1836, p. 498. Type 0. sonneratii = 

 O. nigromarginatus Eiippell. 



