304 



FISHES 



CHAP. 



In Otolithus (Fig. 180) two short tubular canals are given 



off from the antero- lateral angles of the bladder, each sub- 

 sequently dividing into two elongated, 

 tapering sacs, of which one is directed 

 forwards and the other backwards. In 

 C'orvina lobata (Fig. 181) the lateral 

 margins of the bladder are everywhere 

 fringed with a series of tufts of caeca, 

 each tuft being connected by a short 

 common canal with the cavity of the 

 organ. In the " Drum " {Pogonias chromis) 

 (Fig. 182) each side of the anterior third 

 of the air-bladder has a series of digitately 

 branched caecal appendages, the most 

 posterior of which on each side are con- 

 nected by a tubular canal, also bearing 

 branched caeca, with the corresponding 

 postero-lateral extremity of the bladder. 



CollicMhys ^ has a still more remark- 

 able arrangement. In this Sciaenoid 

 (Fig. 183) twenty-five tubular branches 



are given off from each side of the bladder, all of which soon 



subdivide into a dorsal and a ventral 



division. These still further divide, and 



their branches either end blindly or are 



prolonged into a series of arches to the 



mid-dorsal or mid -ventral line as the 



case may be, where they become con- 

 tinuous with the corresponding branches 



of the opposite side. The series of dorsal 



branches, enveloped in their peritoneal 



investment, extend between the body of 



the air-bladder and the roof of the body- 

 cavity, while the corresponding ventral 



branches, similarly invested, surround 



that part of the coelom which contains 



the stomach, intestine, and liver. 



{d) In addition to the subdivision of 



the cavity of the air-bladder by the externally obvious, trans- 



FiG. 180.— Air-bladder of 

 Otolithus. (From Cuvier 

 aud Valenciennes. ) 



^^ffk 



Fro. 181.— Air-bladder of 

 Corvlna lobata. (From 

 Cuvier and Valenciennes.) 



' Giinther, Brit. Mus. Cat. Fishes, ii. 1860, p. 313. 



