436 



TELEOSTE1 



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

 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 wbnlosa, Q. and G. (After Giinthcr.) 



Naseus, Cuv. ', Acanthurus, Forsk. (Fi^r. 446) tropical seas ; Eocene, 

 Europe. Aulorhamplius, de G., Eocene ; and Apostasis, Kr., Miocene, 

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



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 rays, 

 may disappear altogether. 

 The gill -opening is very 

 narrow (Regan [344]). 



Fio. 446. 

 Acanthurus leucostemum, Benn. (After Gunther.) 



complete gills are present, 

 skull. 



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 

 The orbit is carried very high up on the 



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- 

 teen vertebrae. The teeth are conical or incisiform. Branchial opening 

 quite small. 



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



