885 
GRAY 
curve of the back becomes more elevated, while the 
ventral profile 'is rendered more or less straight. In 
front the dorsal margin is broadly convex or, on the 
head, even fiat; but towards the beginning of the dorsal 
fin it gradually becomes more or less compressed; be- 
hind the dorsal fin it is again flattened. The ventral 
margin in front of the anal fin is broadly convex, at 
the ventral fins even fiat; behind the anal fin it is flat, 
like the dorsal margin of the peduncle of the tail. The 
sides of the body are slightly convex. 
The length of the head from the articular knobs 
of the maxillaries is about equal to the greatest depth 
of the body, but varies conversely to the latter, from 
about 21 to 20 % of the length of the body in young 
Grayling, and from 20 to 18V 2 % thereof in old. The 
head is wedge-shaped, with compressed or only slightly 
terete cheeks. The most characteristic feature in its 
appearance consists in the shallow (sometimes even sharp) 
and broad tip of the snout, which in a horizontal di- 
rection is truncate or slightly curved, but is occasionally 
somewhat prolongated like a beak, if only to a short 
distance, and which, when the mouth is closed, always 
projects beyond the point of the lower jaw. The eyes 
show the peculiarity that the pupil, as in the Gwyniads, 
is anteriorly somewhat pointed, at an angle. Their size 
varies with age, the longitudinal diameter being in 
young specimens about 29 %, in old about 16 %, of 
the length of the head. The nostrils are set somewhat 
nearer to the eyes than to the tip of the snout, the 
anterior on each side being raised in a tubular form, 
the posterior, which lies just behind, resembling a trans- 
verse slit, covered by a dermal fold from in front. The 
lips are quite flesh}% especially on the intermaxillaries; 
and the form of the broad, but short gape is essentially 
determined by the said bones. These bones are reduced 
each to a thin, triangular disk, transversely set and 
consisting principally of the articular process, only the 
lower, toothed margin, which is also the true corpus 
of the bone, being somewhat thickened. The maxil- 
laries are terete in the anterior, inward part (the ar- 
ticular process); but behind this point they are disk- 
shaped, curved like a sword, but of fairly uniform 
breadth. The teeth extend along about the middle 
third of their inferior margin. The oblong jugal bone 
is about 2 / 3 as long and 1 / 2 as broad as the maxillary. 
The length of the maxillaries is less than in any pre- 
ceding Salmonoid genus, varying between 35 and 27 % 
of that of the head, or between 48 and 38 % of that 
f LING. 
of the head reduced. Together with the jugal bone 
the maxillary bone varies in breadth between about 
v 4 (in the young) and 2 /s (hi old specimens) of its 
length. The lower jaw is deep at the middle, but at 
the broad anterior margin shallow, almost sharp. Its 
length is about 54 — 48 % of that of the head or 76 
— 66 % of that of the head reduced. The distribution 
of the teeth in the mouth and pharynx we have al- 
ready touched upon. The teeth are all alike, of a 
blunt conical or cylindrical shape, in contradistinction 
to the pointed and more or less curved teeth of the 
preceding genera. The characteristic features of the 
gill-rakers we have also noticed. In the upper jaw 
we find a well-developed transverse fold (palatal cur- 
tain), partially concealing the vomerine teeth, behind 
the intermaxillary teeth. The lower jaw is not with- 
out a similar fold, but this is very low. The pseudo- 
branchiae are rather large, the length of their longest 
lamella (at the middle) being about equal to the ver- 
tical diameter of the pupil. The gill-openings are 
large, extending from the middle of the upper oper- 
cular margin down to the isthmus in about a line with 
the anterior margin of the eye, where they cross each 
other for a little distance, the left fitting into the 
double fold of the right, as we have observed in Mal- 
lotus. All the branchiostegal rays are fiat, the anterior 
(lower) curved in an ensiform shape. Behind they 
gradually increase both in length and breadth. The 
operculum is obliquely quadrangular, with the upper 
posterior corner rounded, the posterior margin more 
or less concave, and the inferior margin obliquely 
ascending in a backward direction along the suboper- 
culum, the length of which measures at this margin 
about 26 — 31 % of that of the head, and the breadth 
(height) of which is about half that of the operculum. 
The lower posterior corner of the suboperculum is 
sharply rounded. The hind margin of the preoper- 
culum is broad, and its lower posterior corner almost 
rectangular. 
The dorsal fin begins at a distance from the tip 
of the snout (the articular knobs of the maxillaries) 
that measures on an average 36 — 34 % (exceptionally 
38 or 33 %) of the length of the body. The average 
length of its base, which increases even relatively with 
age and is greater as a rule in the males than in the 
females, varies between about 18 and 28 V 2 0// ° (hi old 
males exceptionally 25 %) of that of the body. Its 
shape shows great variations. Sometimes (especially 
