Acanthopterygii ; Synentognathi 209 



separate orders. Some of them are more related to the perch, 

 others rather to ancestors of salmon or pike, while still others 

 are degenerate offshoots, far enough from either. 



On the whole, all these forms, medium, extreme and tran- 

 sitional, may well be placed in one order, which would include 

 the primitive flying-fishes and mullets, the degraded globefishes, 

 and the specialized flounders. As for the most part these are 

 spiny-rayed fishes, Cuvier's name Acanthopterygii, or Acanthopteri, 

 will serve us as well as any. The Physoclysti of Muller, the 

 Thoracices of older authors, and the Ctenoidei of Agassiz in- 

 clude substantially the same series of forms. The order Teleo- 

 cephali of Gill (reXeos, perfect; KeQahrj, head) has been lately 

 so restricted as to cover nearly the same ground. In Gill's 

 most recent catalogue of families, the order Teleocephali in- 

 cludes the Haplomi and rejects the Hemibranchii, Lophobranchii, 

 Plectognathi, and Pediculati, all of these being groups charac- 

 terized by sharply defined but comparatively recent characters 

 not of the highest importance. As originally arranged, the order 

 Teleocephali included the soft-rayed fishes as well. From it the 

 Ostariophysi were first detached, and still later the Isospondyli 

 were regarded by Dr. Gill as a separate order. 



We may first take up serially as suborders the principal 

 groups which serve to effect the transition from soft-rayed to 

 spiny-rayed fishes. 



Suborder Synentognathi. Among the transitional forms be- 

 tween the soft-rayed and the spiny-rayed fishes, one of the most 

 important groups is that known as Synentognathi (o-vr, to- 

 gether; ev, within; yvatios, jaw). These have, in brief, the fins 

 and shoulder-girdle of Haplomi, the ventral fins abdominal, the 

 dorsal and anal without spines. At the same time, as in the 

 spiny-rayed fishes, the air-bladder is without duct and the 

 pectoral fins are inserted high on the side of the body. With 

 these traits are two others which characterize the group as a 

 suborder. The lower pharyngeal bones are solidly united into 

 one bone and the lateral line forms a raised ridge along the 

 lower side of the body. These forms are structurally allied 

 to the pikes (Haplomi), on the one hand, and to the mullets 

 (Percesoces), on the other, and this relationship accords with 

 their general appearance. In this group as in all the remain- 



ii 14 



