IV. 



VERTEBRATA: PISCES, TELEOSTEL 



57T 



Order III. Acanthopteri (Acanthopterygii). 



This is the largest group of fishes, its members usually having 

 the ventral fins thoracic in position and more than three rays spiny 

 in dorsal, anal, and ventral fins. The sticklebacks (GASTERO- 

 STEID^E) and some other forms have the pharyngeal bones reduced, 

 the ventral fins farther back, and form the group Hemibranchii. 

 Gasterosteus.* The perch of fresh water (PERCID^E), Perca* 

 and Micropterus* (black bass), and the marine SERRANID.E, some 

 of which are hermaphroditic, have ctenoid scales. The SCOMBRID^E, 

 with Scomber* the mackerel, and TJiynnus* the horse mackerel, and 



Fio. 605. Scomber scomLrus, mackerel. 



the XIPHIID^E, or sword fishes, in which the snout is prolonged into 

 a long sword, are the most important edible fishes of the group. The 

 LORICATI, including the sculpins (Coitus,* Hemitripterus,*)trQ- 

 quently have the body armored with bony plates. The EMBIOTOCID^E, 

 or surf perches of the Pacific, are viviparous. The suck fishes, 

 Remora,* Echeneis,* have the first dorsal modified into a sucker on 

 the top of the head. 



Order IV. Anacanthini. 

 These are soft-finned fishes in which the ventral fins lie in 



FIG. 606. Gadus morrhua* cod. (After Storer.) 



front of the pectorals. Structure goes to show that these have 

 descended from Acanthopteran forms. With few exceptions 



