GRAY MULLETS. 
329 
in front of the eye, with a preorbital bone, serrated at 
the posterior and outer (lower) margins, and performing 
its rooting function in the search for food. The teeth 
of the mouth are either weak or replaced by flexible 
bristles, enamelled only at the tip. These bristles, how- 
ever, are not mere dermal growths, but originate from 
the dental margins of the intermaxillary bones them- 
selves and of the lower jaw, which margins seem coated, 
as it were, with a layer of dentine, broken into closely 
set bristles. In the upper jaw, which is furnished with 
a fleshy and often considerably tumid lip above the 
intermaxillary bones, these bristles project beyond the 
labial margin; but the lower jaw has a sharp edge, 
turned outwards and generally without any external 
traces of bristles. At the tip (above the symphysis) 
the lower jaw is furnished with two hard protuberances, 
which fit into a corresponding incision at the middle 
of the margin of the upper jaw. The mouth is pro- 
trusile, though not to any great extent, the nasal pro- 
cesses of the intermaxillary bones being broad, but 
short. This is the nature of the apparatus of the jaws 
in the more typical Mugiloids; and everything that is 
conveyed into the mouth by means of this apparatus, 
including a great number of indigestible substances 
mixed with the food, undergoes in the pharynx a pre- 
liminary process of mastication and filtration. The 
pharynx is constructed especially with a view to this 
purpose. The skin of the palate and tongue is closely 
set with tubercles and often even with small teeth; and 
the pharyngeal bones form the framework of thick swell- 
ings which obstruct the pharyngeal cavity and the 
opening of the oesophagus. The upper pharyngeal bones 
are broad and curved into a slightly patelliform shape, 
with the convex side downwards, pointed in front, but 
more rounded behind. They rest on a soft, but thick 
layer of fat on the under surface of the skull, and are 
covered by a skin thickly set with tubercles and partly, 
at the inner margin, with small teeth. Between and 
behind the upper pharyngeals there also lies on each 
side a swelling will a soft, adipose base; but at the 
middle of the roof of the palate there runs a groove 
into which the lower pharyngeal bones and the base of 
the tongue (the copular row of the hyoid bone) fit. 
The gill-rakers are comparatively short, but dense and 
fine. Here the mouthful of different substances is chew- 
ed , and the larger pieces of the indigestible part rejected. 
The inside of the oesophagus is furnished with long fila- 
ments, amongst which a copious secretion of mucus is 
collected. The stomach proper is comparatively small and 
thin-walled, with the bottom in the form of a short blind 
sac; but the pyloric part, which is distinctly separated 
therefrom, in the typical Mugiloids is thick-walled and 
furnished with a strong muscular covering, and calls to 
mind the craw of a bird. The pyloric appendages are few, 
generally 6—8 and sometimes only 2. The intestine is 
extraordinarily long and lies in numerous coils, sometimes 
as many as 20. A digestive canal of this length is rare 
among the class of fishes'". The whole of the digestive 
apparatus bestows upon the Gray Mullets a great capa- 
bility of extracting nourishment from the substances of 
which their food is composed; and they also belong to 
the fattest, most active and most prolific of all fishes. 
The skeleton is in several points worthy of notice. 
The broad top of the cranium is convex and smooth, 
without any projecting osseous ridges, its great breadth 
being due to the space required by the pharyngeal 
cavity to contain the masticatory apparatus described 
above. The ridges which issue in a backward direction 
from the upper occipital bone, the mastoid bone (epoticum), 
the pterotic bone and even the styloid bone ( opisthoti - 
cum), on the other hand, are all the longer and some- 
times of an extraordinary length. The first-mentioned 
ridge ( crista ossis occipitis) advances above the extra- 
ordinarily long lateral parts of the occipital bone, and 
meets the neural spine of the first vertebra. The mastoid 
bone sends out a foliate, somewhat bent, osseous pro- 
cess, which may attain a length almost half that of the 
head, and is continued in the flesh to a point vertically 
above the second vertebra. This process may well be 
regarded as an ossification of the muscles. To the outer 
side of the base of this process is attached the upper 
prong of the posttemporal bone, while the shorter lower 
prong joins the process of the styloid bone. The posterior 
process of the squamosal bone is shorter than that of 
the mastoid bone, though it may extend to a line with 
the beginning of the last third of the gill-cover, but 
stronger in proportion and of a pointed, triangular shape. 
The upper neural spines and transverse processes of the 
first six vertebras are also well -developed, the former 
being extended into disks in the longitudinal direction 
of the body; and as the corresponding interspinal bones 
are equally broad 6 , a continuous osseous roof is thus 
a We find the nearest approach in this respect to the Gray Mullets in certain of the Carps and Chfetodonts. 
h See Agassiz, Poiss. Foss., All., tome V, tab. F , fig. 2. 
S c a n cl i n a v i a n Fis lies. 
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