CHAPTER VIII. 

 SUB-CLASS (AND ORDER) TELEOSTEL* 



Fishes with a bony endoskeleton, distinct, usually amphicoelous, 

 vertebrae, a supraoccipital bone, pectinate gills, a branchial oper- 

 culum and usually a hyoidean pseudobranch. Without spiracle, 

 conus arteriosus, optic chiasma, and intestinal spiral valve. An 

 air-bladder is often present. The gonads are usually continuous 

 with their ducts, and the testes are not connected with the kidney. 

 The eggs are heavily yolked, but usually small, and the young are, 

 with a few exceptions, hatched in an immature condition and 

 undergo a larval development. 



The Teleostei include the vast majority of living fishes. They 

 are found in freshwater as well as in the sea, and in some cases 

 they possess organs which enable them to exist in or to breathe 

 air (Anabas, Periophthalmus, fishes which live in foul or muddy 

 water, e.g. many marsh fishes). 



The form of the body is exceedingly variable, most often it is 

 typically piscine, but it may be elongated and snake-like as in 

 the eels, strongly compressed laterally in the ribbon-fishes 

 (Trichiurus, etc.) and in the flat-fishes (Pleuronectidae), or the 

 vertical axis may equal or even exceed the longitudinal in 

 length (Orthagoriscus). The tail which is usually the principal 

 organ of locomotion is in the last-named modification so much 

 reduced that it appears to be absent, and in the sea-horses 

 (Hippocampus) it is without caudal fin and is used as a pre- 

 hensile organ. 



The body is divided into head, trunk, and tail ; the gill- 

 opening usually marks the boundary between the head and 



* See, besides the works of J. Miiller, Gxinther, Day, Jordan and Ever- 

 mann, Boulenger, Bridge, already cited, G. B. Goode and T. H. Bean, 

 " Oceanic Ichthyology," Memoirs of the Museum of Comparative Anatomy 

 at Harvard College, 22, 1896. 



