492 



ANATOMY OF VERTEBRATES. 



32G 



is, Lactarius delicatulus). Comma trispinosa, fig. 326, has 

 two slender crecal processes from each side of its air-bladder ; the 



Bearded Umbrina has three such processes; the 

 allied ( Maigre ' and other species of Sciccutt, 

 with most of the Corvince, have very numerous 

 lateral pneumatic crcca, which, as in Johnius 

 lolatus, fig. 327, are more or less ramified. 1 In 

 some species of Chcilonemus and Gadus blind 

 processes are continued from both the sides and 

 ends of the air-bladder (see the anterior ones 

 in Gadus callarias, fig. 321, A, p). In Gadus 

 Navavac/a the lateral productions expand, and 

 line corresponding expansions or excavations of 

 the abdominal parapophyses, thus foreshadow- 

 ing the pneumatic bones of birds. In Kurtus the 

 air-bladder is encircled by expanded ribs, curving 

 and meeting below it.' 2 



The proper walls of the air-bladder of ordi- 

 nary Osseous Fishes consist of a shining silvery 

 fibrous tunic, the fibres being arranged for the 

 most part transversely or circularly, and in two 

 layers fig. 229, q r; they are contractile and elastic; but 

 the walls of the anterior compartment of the air-bladder of 



Cyprinoids, ib. p, are much more elastic than 

 those of the posterior one. The air-bladder 



is lined by a delicate mucous membrane, with a 



. 

 ' plaster epithelium ; ' it is more or less covered 



by the peritoneum. Its cavity is commonly 

 simple ; in the Sheat-fish it is divided by a 

 vertical longitudinal septum along three-fourths 

 of its posterior part. 3 The lateral compart- 

 ments are subdivided by transverse septa in 

 many other Siluroids (e. g. genus Bagrus) : the 

 large air-bladder of some species of Erythrinus 

 (e. g. E. salmis, E. tcsniatus) is partially subdi- 

 vided into smaller cells. The cellular subdivi- 

 sion is such in the air-bladder of the Amia, that 

 Cuvier compared it to the lung of a reptile 4 ; 

 an< l th e transition from the air or swim-bladder 



Air-bladder, Corvina 



trispinosa, 



327 



1 xxxix. i. p. 94, after Cuvier and Valenciennes, xxm. pi. 13S, 139. The most 

 complex form is that described by Giinthcr (CLXXIV, vol. ii. p. 313) in Cullichthys 

 lucida, where the air-bladder forms a second investment of the abdominal viscera, 

 within the peritoneum. 



CLXXIV. vol. ii. p. 10. 3 ex vi. vol. ii. p. 33, pi. 6, fig. 4. 4 xxiv. vol. ii. p. 377. 



