ECONOMIC ZOOLOGY 



*l 



$s a o 

 j 3 



>* 



iifii 



!l 



**< : 



|a|3Ji 

 g^-g 

 ^.s^ss 

 **ja>s 

 I i a 1 



fc4 O 0> 



W 



^ - 



^ s s 



"4T35S 



x Sis o> e 



^""l! 



O -H bo o 



ni rrt ^H -*A ZL 



' 



S "5 



g S5^ 



v-g^ 



1^2 



T3 



83 



s|-i 



to 

 e J2 



r^H dj 



^-^ bo ^ 

 *^ 



^ 



ll 



^'o ^ 

 ftocfi a 



I *a 

 ^^ e 



"O v^l 



a 



bo 



14 

 :i 



^1 



s". 

 & 



s 



C r^ ff.9 



t s. 



The subphylum vertebrata, the 

 most important of all the animal 

 groups, is variously divided, by 

 different authors, into classes. The 

 older classification was into five 

 classes: I. Pisces; II. Amphibia; 

 III. Reptilia; IV. Aves; and V. 

 Mammalia. As a matter of con- 

 venience this classification will be 

 followed here, though it is now usu- 

 ally customary to substitute for the 

 first class three the Cyclostomata, 

 lampreys and hags; Elasmobranchii, 

 sharks, rays, etc.; and Pisces, the 

 bony and other more or less typical 

 fishes. 



The enormous importance of 

 fishes as food and in other ways will 

 be discussed later; a few of the ways 

 in which the class is injurious to 

 man will first be noted. 



Cyclostomes, Fig. Si. This low 

 group of fishes, characterized by the 

 circular, suctorial mouth, the absence 

 of paired fins, the persistent noto- 

 chord, and other primitive charac- 

 ters, comprises the lampreys (Petro- 

 myzon) and hags (Myxine; Bdello- 

 stoma) most of which are marine 

 and vary in size from 6 to 36 inches. 

 In olden times lampreys (lamperns) 

 were used as food; now they are 

 seldom if ever eaten in this country 

 and their chief importance is the 

 damage they do to valuable food- 

 fishes. The larger lampreys attach 

 themselves to the bodies of other 

 fish and, by the rasping action of 



