IV. VERTEBRATA: PISCES, TELEOSTEI. 



511 



Order III. Acanthopteri (Acanthopterygii). 



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. Sticklebacks (Gasterosteid^) and some other forms have the pharyn- 

 geal bones reduced, the ventral fins farther back, and form the group Elemi- 

 branchii. Gastcrosteus.*- The perch (Peecid^), and the marine Seeranid/E 

 have ctenoid scales. Scombrid.-e, mackerel, Xiphiidjs, sword fishes; snout 

 prolonged into a long sword; Loeicati, sculpins (Cottus,* Hcmitriptcrus*). The 

 Embiotocid/e, surf perches of the Pacific, viviparous. The suck fishes, Remora* 

 first dorsal modified to a sucker on top of head. 



Order IV. Anacanthini. 



Soft-finned fishes with ventral fins in front of pectorals; descended from 

 Acanthopteran forms. With few exceptions (Lota* burbot), marine. Gadid^, 



Fig. 561. — Cadus monhua* cod (after Storer). 



cod and haddock; Pleuronectid^ (flat fishes), halibut, flounders, sole. The 

 PleuronectidcB, from their asymmetry, need a word. The young are perfectly 

 symmetrical, but the animals turn on one side, the lower becoming white. The 

 eye of this side shifts to the upper side, twisting the bones of the skull in its 

 progress. 



Fig. 562. — CMlomyclerus geometricus* swell fish (after Goode). 



Order V. Lophobranchii. 



Marine species, having gills composed of rounded tufts, body covered with 

 a segmented armor of bony plates and peculiar breeding (p. 510); sea horses, 

 Hippocampus *■ pipe fishes, Syngnathus* 



