VISCEEAL ANATOMY OF THE CHAEACINID^. 69 



9. Cltjpea. Clnpeci sprattus and Clupea harengus. — As is well known, tlie duct is 

 fairly long and opens medially into the extreme posterior end of the blind sac (fig. 25). 



10. Chirocentrus. Chirocentrus dorab (1 specimen). — In this fish, marked out as 

 primitive by its intestinal spiral valve, the wide ductus pneumaticus opens medially into 

 the dorsal surface of the stomach rather behind the middle of the blind sac, which is of 

 enormous length (fig. 26). 



11. Galaxias. Galaxias truttaceus (3 specimens). — The long duct opens far back on 

 the stomach, quite near the extremity of the short blind sac, much on the same level as 

 in Albida ; but it is not median, being in fact very markedly displaced to the right 

 (fig. 27). 



12. Esox. Esox lucius (5 specimens). — The short duct opens far forward into the 

 dorsal wall of the oesophagus. It is nearly median, but in all the specimens examined 

 was just appreciably to the left side (fig. 28). 



13. Ctprinobontid^. Cyprinodon calaritanus, Orestias Oioeni, Fundidus robustiis, 

 and Goodea atripinnis (2 or more specimens of each). — Diminutive size here presented 

 an obstacle, in most cases, to satisfactory observation, but in Orestias the duct was clearly 

 made -out to be situated far to the right of the mid-dorsal line. Apparently this was 

 also the condition existing in Fimdulus and Cyprinodon. The specimens of Goodea 

 were not in sufficiently good condition for a satisfactory observation. 



14. Percopsid^e. Fercopsis guttatus (2 specimens) and Columbia (ransmontana 

 (1 specimen). — In both these forms the ductus puevimaticvis opens into the oesophagus 

 far to the right side of the mid-dorsal line. 



15. Htodon. JSyodon alosoides (3 specimens). — -The sliort, wide duct opens far 

 forward on the oesophagus, nearly mid-dorsally, but, somewhat doubtfully, a little to the 

 right side. 



16. Anguilmd^. Conger conger (2 specimens). — In both cases I found the duct so 

 difficult to trace, that I cannot commit myself to any statement as regards its relations 

 with the alimentary canal. 



17. Halosatjrus. Salosaurus macrochira (1 specimen). — The rudimentary air-bladder, 

 situated in the posterior part of the body-cavity, narrows in front into a band Avhich is 

 continued as a thread-like ligament. This ligament, apparently solid, terminates in the 

 mid-dorsal wall of the stomach quite near to its posterior end, not, as iias been stated *, 

 in the oesophagus. 



Finally, in the three Ganoids Acipenser, Amia, and Lepidosteus, as I have verified, 

 the communication of the air-bladder with the oesophagus is in the mid-dorsal line. 

 In Acipenser the duct is of some length, but in Amia and Lepidosteus the bladder opens 

 directly by a slit-like orifice into the oesopliagus. 



* Giintlier, iu the lleporfc on the Voyage of the ' Challenger,' " Deep-sea Fishes," vol. xxii. Zool. 1887, p. 232. 



