88 PISCES. 



PalsBoniscids, and in Dictyopyge at least the supports of the 

 anal fin are recorded as fewer than the apposed dermal rays. 

 The head-bones are well developed and ganoid ; the eye is far 

 forwards, the snout prominent, and the gape of the mouth 

 wide. A series of branchiostegal rays is present. The scales 

 are all rhombic and ganoid. Catopterus, which exhibits the 

 origin of the dorsal behind that of the anal fin, occurs in the 

 Triassic black shales of Connecticut, Massachusetts, and New 

 Jersey, U.S.A. The typical species of Dictyopyge, which has the 

 dorsal fin further forwards, is only found in the corresponding 

 rocks of the Richmond Coalfield, Virginia (D. macrura); but 

 other forms are met with in the Keuper of Tyrone (Ireland), 

 Warwickshire, and Coburg, in the Bunter of Switzerland, and 

 in the supposed Triassic of New South Wales. 



In strata of Triassic and Liassic age there are remains of 

 another interesting family of fishes, which resemble the 

 Palseoniscids in the non-correlation of the endoskeletal supports 

 with the exoskeletal rays in the dorsal and anal fins, but 

 exhibit an abbreviate-diphycercal tail. These are the Belono- 

 rhynchidae, characterized by a remarkably elongated and 

 slender trunk, remote and short-based dorsal and anal fins, 

 and a discontinuous squamation, the flanks exhibiting isolated 

 longitudinal series of scutes. The only definable genus hitherto 

 discovered is 



Belonorhynchus (fig. 65). The snout is much elongated, and the 

 upper and lower jaws are approximately equal in length. The cranium is 

 completely enveloped in membrane-bones, which are more or less fused 

 together in the adult and firmly connected at the side in advance of the 

 orbit with the similarly fused cheek-plates. The constitution of the 

 cranial shield is not satisfactorily known, ifrut it extends backwards 

 beyond the skull to the hinder border of the operculuni ; the parasphenoid 

 at the base of the skull is similarly produced backwards. The orbit is 

 large, and there is a hardened, perhaps ossified sclerotic ring. The nasal 

 opening is single on each side, and obliquely elongated. One long 

 posterior suborbital bone is distinct, deepest behind, and produced as a 

 narrow bar beneath the orbit ; but nothing further is definitely known 

 concerning the facial bones. The mandible is very deep behind ; the 

 angular and articular bones are fused together, and the expanded outer 

 surface of the former is marked by radiating branches from the sensory 

 canal which traverses its length. The dentition on the margin of both 



