38 THE ANGLER-NATURALIST. 



This arrangement of the gills is peculiar to this 

 Order, which, moreover, have the gill-covers entirely 

 closed behind, with the exception of a single small 

 hole. Only one Family. 



Order VI. PLECTOGNATHI, or Fishes with soldered jaws. 

 (From Gr. plekein, to bind, and gnathos } a jaw.) 

 This Order has no true ventral fins. Many of its 

 characteristics resemble those of the Cartilaginous 

 fishes. The chief peculiarity is, the maxillary bone 

 being soldered to the side of the int er -maxillary , 

 which constitutes the upper jaw in other words, the 

 jaw-bones being soldered together. Two families. 



The CARTILAGINOUS FISHES, or CHONDRO- 

 PTERYGII (from Gr. chondros } cartilage, and pterygion, 

 a fin), consist of two Orders, viz. : 



Order I. CHONDROPTERYGII BRANCHIIS LIBERIS, or Carti- 

 laginous Fishes with free gills. (From Lat. branchia, 

 gills, and liber , free.) The fishes forming this Order 

 have a single wide opening in their gills, and a 

 gill-cover as in the Bony Fishes ; but no gill-rays. 

 The Order contains two Families. 



Order II. CHONDROPTERYGII BRANCHIIS FIXIS, or Carti- 

 laginous Fishes with fixed gills. (From Lat. branchiae, 

 gills, and fixus, fixed.) These fish have their gills 

 fixed at the outer edge, with a separate opening 



