MALACOPTERYGII. 215 



Fam. 5. Notopteridae, with one genus Notopterus, f. w. of E. Ind. 

 and W. Afr. 



Fam. (5. Osteoglossidae. Body covered with large mosaic-like scales ; 

 head scaleless, its integument confluent with the bone ; dorsal fin on tail 

 and opposite anal ; gill openings wide, pseudobranch absent ; air- 

 bladder simple or cellular, stomach without caecal sac, pyloric append- 

 ages two. Eggs fall into body cavity. Large f. w. fishes of the 

 tropics. 4 genera. Osteoglossum Vandelli, S: Amer. ; Ara- 

 paitna Mull., Brazil and Guyanas ; Heterotis Ehr., trop. Afr.; Sclero- 

 pages, Australia, E. Ind. Arch. Excluding the E. Ind. Archipelago, 

 the distribution of this family is the same as that of the Dipnoi. 

 Heterotis niloticus forms a nest and the young larvae have external gills. 



Fam. 7. Pantodontidae. One genus, f. w.,W. Afr., pectorals very large. 



Fam. 8. Ctenothrissidae. Extinct, Cretaceous. 



Fam. 9. Phractolaemidae. One genus, W. Afr. 



Fam. 10. Saurodontidae (Ichthyodectidae). Extinct, Cretaceous ; 

 Portheus, Ichthyodectes. 



Fam. 11. Chirocentridae. One genus, Ind. Ocean and Seas of China 

 and Japan. 



Fam. 12. Salmonidae. Body generally covered with scales, head 

 scaleless ; margin of upper jaw formed by maxillaries and premaxillaries , 

 a small adipose fin behind the dorsal ; pyloric caeca generally present 

 and numerous ; air-bladder large and simple with a pneumatic duct ; 

 pseudobranch present ; no oviducts. Inhabitants of sea and f. w. ; 

 most of the mar. genera are from the deep sea ; most of the f. w. 

 forms are peculiar to the temperate and arctic region of the Northern 

 Hemisphere, one occurring in New Zealand ; many f. w. species are 

 anadromous ; no fossils of f. w. species known. Osmerus and other 

 genera from the Miocene. 



Salmo Art., trout, salmon and charr, inhabitants of f. w., many 

 species descending to the sea after spawning (anadromous), the young 

 of all are barred, the bars vanishing in adult except in small varieties ; 

 many of the species are highly variable and capable of considerable adapta- 

 tion to their surroundings ; the marine forms usually silvery with or 

 without black spots, the f. w. forms more or less speckled with 

 black and red. Some individuals of full size are sterile, but this is pro- 

 bably only a temporary condition ; overgrown individuals are sterile ; 

 anadromous fish, generally return to their native river. River and sea 

 trout have been acclimatised in Tasmania and N. Zealand, and appar- 

 ently in India. As these species are highly variable in response to change 

 of condition the observation of these acclimatised races will afford an 

 extremely interesting study. 



S. salar L., salmon, N. Hemisphere between latitudes 45 and 

 75 ; does not occur in rivers opening into Med.,* the last Thames salmon 

 was caught in 1833 ; a marine fish ascending rivers to spawn (Sep. to Jan. 

 in Britain), the nest or redd is dug out by the female in gravel 

 and the eggs are buried ; young salmon of the first and second 

 year are called parr or pink (4 to 6 in.) ; they then become smolts, 

 which descend to sea, and reascend the rivers as grilse, which having 

 spawned go to the sea and return as salmon ; a salmon which has spawned 

 is a kelt, kelts go to the sea, and probably reascend next year ; kipper 

 is a male kelt, or a salmon which has been detained in f. w. and got 



* Not even in those of Macedonia, notwithstanding Fluellen (Henry 

 V., Act 4, Sc. 7) ! 



