506 PISCES SUB-CLASS I1I.TELEOSTOMI. 



dredging. When brought to the surface, owing to the sudden diminution of 

 pressure, their eyes start out of the sockets, the scales stand erect, and the 

 flesh is loose and fragile, so that the preservation of specimens is frequently 

 a matter of considerable difficulty. 



These two unimportant families, severally represented by a single type, 

 may be distinguished from the preceding members of the Isospondyli by the 

 circumstance that the supraoccipital bone of the skull ex- 

 Families Chiro- tends forwards so as to separate the two parietals from one 

 centridce and another. And in this feature they agree with the members 

 Bathythrissidm. of the following families of the section, except for a few 

 aberrant types of two. The first family is represented by 

 the dorab (Chiroceidrus dorab), of the Malayan and Red Seas, and is dis- 

 tinguished by the possession of but one caudal vertebra. The dorab is a large 

 elongated fish, with a deeply-forked tail, no fatty fin, an up-turned muzzle, 

 powerful teeth, and a sharply-keeled and serrated under surface. In length 

 it is stated to grow to as much as twelve feet. Very different is the deep-sea 

 Bathythrissa dorsalis of Japan, in which the body is deep and oblong, with 

 the under surface rounded, the head naked and without barbels, and the 

 dorsal fin so much elongated as to occupy nearly the whole length of the 

 back, a fatty fin being wanting. This fish forms an exception to the gener- 

 ality of the members of the sub-order in lacking an air-bladder. 



The familiar "red-herring," in its natural condition, is the type of a family 

 of mostly marine and littoral fishes whose importance as a food-supply can 

 scarcely be overrated. Limits of space, unfortunately, 

 Herrings. allow of only a very inadequate notice of the group. Dr. 

 ~, * y Giinther writes " that the family of herrings is probably un- 

 upei ce. surpassed by any other in the number of individuals, al- 

 though others comprise a much greater variety of species. The herrings are 

 principally coast fishes, or at least do not go far from the shore ; none belong 

 to the deep-sea fauna, scarcely any have pelagic habits, but many enter or 

 live in fresh-waters communicating with the sea. They are spread over all 

 the temperate and tropical zones. " With the exception of one genus, agree- 

 ing with the Cfliirocentidce in the structure of the skull and presence of a 

 single caudal vertebra, the Clupeidce are specially characterised by the want 

 of a fatty fin, and the general presence of small plates of bone on the lower 

 surface of the body, which is usually sharp and often serrated. The head 

 is devoid of barbels, and usually also of scales, but the body is always fully 

 scaled, although the lateral line is generally wanting. The margin of the 

 upper jaw is formed in part by the premaxillse, and in part by the maxillre ; 

 each of the latter bones consisting of three distinct elements. Usually the 



gill-openings are complete, and the 

 operculum comprises the full number of 

 elements. The rays of the short dorsal 

 fin are few and weak, although those of 

 the anal may be numerous. The air- 

 bladder is comparatively single, and 

 most members of the family are fur- 

 fig. 30, THE HERRING. nished with false gills. In the typical 



genus Clupea the two jaws are sub-equal 



in length, the eyes have fatty lids, and the body is compressed, with the 

 abdomen serrated inferiorly as far forwards as the chest. The cleft of the 

 mouth is of moderate width, and if teeth are present at all, they are rudi- 



