330 
SCANDINAVIAN FISHES. 
formed above the anterior part of the spinal column, 
back to the insertion of the first dorsal fin. All this 
singular development of bone gives increased firmness 
to the front part of the body, and strengthens the points 
of origin of the upper lateral muscles of the body and 
the marginal muscles of the back. The same strength 
is given to the lateral muscles of the lower part of the 
body and those of the pectoral tins by the deeply in- 
cavated hind margin of the clavicular bone. This bone 
is also furnished on the inner side with a hamate pro- 
cess. Each of the pelvic bones is suspended posteriorly 
by a ligament from the lower postclavicular bone and 
anteriorly from the lower end of the clavicular bone. 
The anterior branchiostegal rays are almost filiform, the 
posterior distallv extended and sword-like. The large 
opercula are longitudinally arched at the top, and thus 
serve both as the roof and outer wall of the gill-cavity. 
They are quadrilateral in shape, but the lower posterior 
corner is obliquely rounded. The preoperculum is more 
or less nearly rectangular, with the anterior margin di- 
ctated. Both the suboperculum and the interoperculum 
are well-developed and fairly uniform in breadth, the 
latter being, however, as usual narrower in front. As 
a rule too, they are covered with scales, as well as, in 
many cases, the posterior (angular) part of the under 
surface of the branches of the lower jaw. The inter- 
opercula generally, and the branches of the lower jaw 
sometimes, meet or even cross each other to a greater 
or less extent under the throat. The branches of the 
lower jaw, however, generally leave a naked chin-space" 
between them, the size and shape of which may some- 
times be of use as a specific distinction. In cases where 
the interopercula do not quite touch, this chin-surface 
is continued backwards by the bare part of the bran- 
chiostegal membranes, which cross each other anteriorly, 
under the isthmus. 
The shape of the preorbital bone too, is often of 
importance in the determination of the species. The 
outer, externally visible part is square; but in its en- 
tirety the bone is rather triangular or polygonal, with 
the posterior and lower (anterior) margins sharply ser- 
rated. In front of and below this bone, and often, when 
the mouth is closed, entirely concealed by it, lies the 
singularly bent and twisted maxillary bone. The arti- 
cular process of the latter is S-shaped and directed at 
a right angle inwards, and is furnished posteriorly with 
a long, convex, articular surface, turned towards the 
point of the ethmoid bone and the top of the head of 
the vomer, which projects in front of the latter, and 
anteriorly, further in, with a similar articular surface, 
turned towards the nasal process of the intermaxillary 
bones. The shaft of the maxillary bone is also bent 
and terete or, at all events, uniformly narrow, with the 
hind part more or less crooked; and on its inner side 
we often find a wand-shaped process, pointing in a back- 
ward (upward) direction. The intermaxillary bones are 
short and deep. The mandible is so twisted that the 
dental part is horizontal, with the dental margin turned 
outwards and forwards and the posterior articular (an- 
gular) part inwards and backwards. 
As we can easily see from the above description, 
the Mugiloids have several points of resemblance to the 
Cyprinoids; but the most striking external resemblance, 
the broad dorsal side of the forepart in conjunction 
with the high position of the pectoral fins, guides us 
towards the Scombreso'cidce and, nearest of all, to the 
Flving-fish. Both the comparisons involve soft-rayed 
fishes, and gain still further significance by the ab- 
dominal position of the ventral fins. Among the 
Acanthopterygians the Mugiloids and Atherines occupy 
a somewhat isolated position. 
Genus MUGIL. 
No teeth proper; mobile , setiform teeth , externally visible , as a rule , only in the upper jaw; margin of the man- 
dible sharp ; mouth transversely placed, and its breadth greater them its length. Nostrils set on the upper side of 
the short and blunt snout , the anterior being small and round, the posterior oblong and transverse. Pyloric part 
of the stomach highly muscular. 
By this limitation the genus Mugil is exclusively Mullets. In spite of this, the genus contains by far the 
reserved for the most typical forms among the Gray greater part of the family, perhaps some seventy spe- 
The space at the chin , between the mandibles: Gunther; espace jugidaire: Moreau. 
