436 



TELEOSTE1 



trichs in the pelvic fin. The teeth vary, but are generally incisiforin. 

 Parapophyses are present bearing ribs and epipleurals. The tail is pro- 

 vided usually with lateral plates or sharp defensive spines. Bony plates 

 near the base of the dorsal spines. A median bony horn develops above 

 the eyes in Naseus. 



FIG. 445. 

 Teuthis nebuloM, Q. and G. (After Giinthcr.) 



Naseus, Cuv. ; Acanthurus, Forsk. (Fig. 446) -tropical seas ; Eocene, 

 Europe. A ulorhamphus, de G., Eocene; and Apostasis, Kr., Miocene, 

 Europe. Zanclus, C. and V. ; Colocopus, Gill ; Prionurus, Lac. tropical 

 seas. 



SUBDIVISION B. The opercular bones become reduced, the myodome 

 and the ribs are lost ; if present the pelvic bones are fused in the middle 



line ; also the pelvic fins, 

 which are reduced to a spine 

 and a few small dermal ray.s, 

 may disappear altogether. 

 The gill -opening is very 

 narrow (Regan [344]). 



FIG. 440. 

 Acanthurus leucosternifin , Uenn. (After Giiiithfr.) 



BRANCH 1. SCLERODERMI. 

 The supraclavicle is vertical 

 and the pectoral radials 

 normally developed (Fig. 

 452, B). The dentary is 

 fused to the articular, and 

 the teeth usually strong and 

 incisor-like (Fig. 448). Four 



complete gills are present. The orbit is carried very high up on the 



skull. 



SERIES 1. The spinous dorsal consists of one or more spines, of which 

 the first immediately behind the skull is generally very large, and, when 

 erect, may be locked by the second. There are generally only about nine- 

 te^n vertebrae. The teeth are conical or incisiform. Branchial opening 

 small. 



A. The pelvic bones are fixed ; but there are still vestiges of paired 



