CHAPTER XII. 



A LARGE proportion of our fresh-water fish belong to the 

 fourth order of the bony fishes, the PHYSOSTOMI (from the 

 Greek words phuse, a bladder, and stoma, a mouth) ; i.e., 

 the air-bladder, if present, has a pneumatic duct. All the 

 fin-rays are articulated ; sometimes the first of the dorsal 

 and pectoral fins are ossified. Ventral fins, if present, are 

 abdominal and without spines. 



Dr. Giinther ("Introduction to the Study of Fishes") 

 divides this order into thirty-one families, of which the 

 third (Cyprinidce), the tenth (Esociace), the fifteenth (Sal- 

 monidce), and the thirty-first (Murcenidce) claim our par- 

 ticular attention. 



The third family Cyprinidce Gunther says, has the 

 " body generally covered with scales, head naked, margin 

 of the upper jaw formed by the intermaxillaries, belly 

 rounded or, if trenchant, without ossifications ; no adipose 

 fin, stomach without blind sac, pyloric appendages none, 

 mouth toothless, lower pharyngeal bones well developed, 

 falciform, sub-parallel to the branchial arches, provided 

 with teeth which are arranged in one, two, or three series ; 

 air-bladder large, divided into an anterior and posterior 

 portion by a constriction, or into a right or left portion 

 enclosed in an osseous capsule ; ovarian sacs closed." 



Day (" Fishes of Great Britain and Ireland") in his 

 definition of this family says : " A single, rayed, dorsal 

 fin ; ventrals inverted posterior to the pectorals, head 

 scaleless, body scaled or scaleless, never covered by osseous 

 plates ; no cul-de-sac to stomach, no pyloric appendages ; 

 air-bladder, if present, large ; it may be divided by a con- 

 striction into an anterior and posterior portion, neither of 

 which are enclosed in bone (Cyprinidce), or into two lateral 



