X. EXPLANATION OF CATALOGUE. 



The Icnrjth of the snout is to the vertical from the anterior margin of 

 the eye. 



The length is from tlie end of the snout to the end of the tail, not 

 including the caudal fin. Wlien the caudal fin is included it is always 

 called tokd length. 



The diameter of the eye is the horizontal diameter. This character, 

 however, must te taken wdth caution, as the size of the eye often varies, 

 and is always greater in pro}x>i-tion in young individuals. 



In the references given after the names of the species, Giinther means 

 his Catalogue of Fishes ; Jenyns means the Zoology of the Voyage of the 

 'Beagle'; Richardson means the Zoology of the Voyage of the 'Erebus' 

 and 'Terror,' and Cat. Col. Mus. stands for the Catalogue of the Colonial 

 Museum, 1870. 



The following outline of Ichthyology has been abridged and re- 

 arranged from Von der Hoven's " Hand-book of Zoology," for the 

 assistance of the student : — 



" Fishes are vertebrate, cold-blooded animals, which live in water and 

 breathe by gills. 



" Body. — The body may be divided into the head, the trunk, and the 

 tail, for there is no proper neck, as the thoi*acic cavity succeeds 

 immediately to that of the mouth, or is even confluent with it. The 

 tail, which is that poi'tion of the body lying behind the vent, miist not 

 be confounded with the tail fin, which is always called the caudal fin. 

 In most fishes the body is comprensed laterally, so that the section is an 

 oval, of wliich the back forms the broadest end. In some, however, as 

 in the Rays, it is depressed, or flat, while in others it is cylindrical, as in 

 the Eels. In general the body is covered with scales (which are called 

 cycloid when they are smooth edged, and ctenoid when toothed like a 

 comb), but sometimes the scales are exceedingly minute, and the smooth 

 skin seems to be naked. In some fish, however, scales are really wanting. 

 On each side of the body lies a line of j^ores or aj^ertures which fonn 

 the lateral line, and it is from these pores that the slimy fluid, with 

 which the body of fishes is covered, is seci-eted. Generally this line is 

 continuous, but sometimes it is interrupted, that Ls, stops before reaching 

 the end of the tail, sometimes ceasing altogether {e.g. Sticharium), or 

 sometimes beginning again lower down (e.g. Notothenia), and pui-suing 

 a new direction on the tail. A few fishes have several lateral lines 

 {e.g. Acantlioclinus), and some none at all (e.g. J/ugil). 



"Gills. — The gills have ordinarily a single opening on each side 

 behind the head (gill opening), through which the water is expelled on 



