TELEOSTEI. 405 



enabling the animal to attach itself to stones and rocks. There 

 is no air-bladder. The body is cylindrical, compressed towards 

 the tail, and destitute of scales. The skeleton consists of a 

 series of cartilaginous rings without ribs. 



In the Myxinidcz the mouth is circular membranous, with 

 eight cirrhi. The palate carries a single fang, and the tongue 

 is armed with a double row of small teeth on each side. There 

 may be seven branchial apertures on each side (Heptatrema), 

 or the branchial pouches open into a common tube on each 

 side, and each of these terminates in a distinct aperture situated 

 under the heart on the lower surface of the body (Gastro- 

 branchus). The Hags pour out so much mucus through the 

 lateral line that they can surround themselves with jelly ; hence 

 the name of the common species (Myxine glutinosd). The 

 Glutinous Hag is a native of the North and British seas, and 

 is chiefly found in the interior of the Cod and Haddock (often 

 five or six individuals in one fish). 



CHAPTER LVI. 



TELEOSTEI. 



i 



ORDER III. TELEOSTEI. This order includes the great ma- 

 jority of fishes in which there is a well-ossified endoskeleton, 

 and it corresponds very nearly with Cuvier's division of the 

 "osseous" fishes. The Teleostei are defined as follows : The 

 skeleton is usually well ossified ; the cranium is provided with 

 cranial bones ; and a mandible is present ; whilst the vertebral 

 column almost always consists of more or less completely ossi- 

 fied vertebrae. The pectoral arch has a clavicle ; and the two 

 pairs of limbs, when present, are in the form of fins supported 

 by rays. The gills are free, pectinated or tufted in shape ; a 

 bony gill-cover and branchiostegal rays being always deve- 

 loped. The branchial artery has its base developed into a bul- 

 bus arteriosus ; but this is never rhythmically contractile, and 

 is separated from the ventricle by no more than a single row of 

 valves. 



The order Teleostei comprises almost all the common fishes: 

 and it will be unnecessary to dilate upon their structure, as 

 they were taken as the types of the class in giving a general 

 description of the Fishes. It may be as well, however, to recapi- 

 tulate very briefly some of the leading characters of the order. 



