BONY FISHES AND GANOIDS. 507 



mental and deciduous. The anal fin is of moderate length, with less than 

 thirty rays, the dorsal fin is placed above the pelvic pair, and the caudal is 

 deeply forked. Among over half a hundred species, we may name the common 

 herring (C. harengus), the spratt (C. sprattus), the alliceshad (C. alosa}, the 

 shad (C. finta), the American mossbanker (C. menhaden}, and the pilchard or 

 sardine (C. pilchardus). Herrings, as is well known, are gregarious and car- 

 nivorous fishes, going about in huge shoals, the presence of which is often 

 indicated not only by the appearance of the surface of the water, but by the 

 flocks of sea-birds which hover overhead in search of prey. The shoals 

 appear to approach the coasts solely for the purpose of spawning, after which 

 they retire to deeper water. Australia is the home of certain fresh-water 

 herrings forming the genus Diplomystus, and characterised by having plates of 

 bone behind the head similar in character to those on the under surface. 

 Another and larger genus (Engraulis) is typified by the Mediterranean 

 anchovy, and is characterised by the prolongation of the nearly conical snout 

 beyond the tip of the lower jaw, and by the eyes being covered with a con- 

 tinuous skin. The Mediterranean species, either preserved whole, or made 

 into a paste, affords the piquant anchovy of commerce. The only other type 

 that can be mentioned here is Elops, which is peculiar in that the parietal bones of 

 the skull are in contact, and also for the possession of two caudal vertebrae. 

 There are two species from the warmer seas, in both of which the space 

 between the two branches of the lower jaw is protected by a thin plate of 

 bone, while the lower surface of the body is rounded and smooth. 



Very brief notice must suffice for two small and unimportant families now 

 generally placed between the closely allied groups of the herrings and salmon. 

 The Alepocephalidce, resemble Elops, and thus the Salmonidce, 

 in having two caudal vertebrae, but differ from the former, Families Alepo- 

 and thereby agree with most of the latter, in that the two cephalidce and 

 parietal bones of the skull are separated by the supra- Haplochitonidce. 

 occipital. They lack, however, the fatty fin of the latter, and 

 barbels are wanting to the head, which is likewise devoid of scales, as is 

 sometimes also the body. Both pairs of jaw-bones enter into the formation 

 of the margin of the upper jaw, and the stomach lacks the blind appendage, 

 or caecum, characterising that of the herrings. In the typical genus Alepo- 

 cephalus the body is covered with thin scales, but in Xenodermichthys these 

 are replaced by fine nodules. Two other genera are known. The trout-like 

 fish from the rivers of Chili and the southern extremity of South America 

 and the Falklands known as Haplochiton, together with the allied Austra- 

 lian genus Prototroctes, represent the second of the two families now under 

 consideration ; the first of these resembling a scaleless trout, whereas in the 

 second the body is scaled and the jaws are armed with minute teeth. These 

 fish differ from the families last noticed in possessing a small fatty fin. In 

 this respect they resemble the Salmonidce, from which they may be dis- 

 tinguished by the fact that the maxillae do not enter into the formation of the 

 margin of the upper jaw. 



From the other allied families the Salmonidce may be distinguished by the 

 possession of a small fatty fin between the dorsal and the tail, coupled with 

 the circumstance that the margin of the upper jaw is formed 

 in front by the premaxillae and at the sides by the maxillae. Salmon Tribe. 

 The inferior aspect of the body is rounded ; and whereas the Family 



skin of the head is invariably naked, the body is generally Salmonidce, 

 clothed with scales. The Salmonidce are in the main re- 



