335 
THICK-LIPPED 
specimens of as great a. length as 665 mm., and ac- 
cording to Day the species may attain a length of 9 
dm. and a weight of 6 2 / 3 kgm. The original of our 
figure is a smaller specimen, a female measuring 3 dcm. 
from the tip of the snout to the end of the middle 
caudal rays, in which one or two of the points most 
characteristic of the species have not yet become so 
distinct as they sometimes do in other cases. In this 
genus too, the significance of the changes of growth 
represents the appearance of the specific differences; 
and among the Scandinavian species Mugil chelo occu- 
pies the highest rank in the generic series of develop- 
ment. The character from which the English name of 
the species is derived, the tumidity of the upper lip, 
which is usually so marked that the height of this lip 
is considerably more than half the longitudinal dia- 
meter of the eye (from about 60 to 70 % thereof), in 
our specimen measures only 53 % thereof or only slightly 
more than it may measure, though it be only in ex- 
ceptional cases, in full-grown specimens of Mugil capito. 
Similar changes of development in conjunction with 
individual variations, render the species of this genus 
extremely difficult to determine. Thus we find in the 
above list of synonyms that this species has borne the 
name of all the three chief species of the genus. 
In its general appearance, apart from the structure 
and position of the fins, the Thick-lipped Gray Mullet, 
like the two following species, reminds us of a broad- 
backed Herring or Gwyniad; but the broad -topped, 
slightly convex and, for the most part, scaly head", 
'with the broad snout, at once gives the Gray Mullets 
a, distinctive feature. The colour is not unlike that of 
the Herring, being a bright, greenish steel-blue on the 
GRAY MULLET. 
back'' and silvery on the belly, but marked with the 
singular, longitudinal, blue streaks, seven or eight in 
number, on the sides of the body. The gill-cover is 
of a- bright golden lustre, which, in young specimens 
at least, is visible through the scales. The pectoral 
fins (scaly at the base) are pale and transparent, but 
more or less strongly tinged with yellow and with a 
more or less distinct black spot at the upper part of 
the base. The ventral fins, like the belly, are milk- 
white with a silvery lustre. All the vertical tins are 
more or less distinctly gray. At least the first three 
rays of the first dorsal fin are covered on the broader 
side with small scales, and all the rays of this fin are 
of the same colour as the back. The second dorsal fin 
and the somewhat paler anal fin (both covered with 
small scales on the fin-membrane in front and at the 
base at least), as well as the caudal fin (with more 
numerous scales both on the fin-membrane and at the 
base of the rays), are ashy blue, which is also the pre- 
dominant colour of the iris, though it has an inner 
ring of a golden colour next the pupil, which is black. 
The greater part of the upper lip is grayish black, but 
interiorly it grows paler and is white at the margin. 
Such was the appearance of the young specimen which 
Mr. C. i\. Hansson forwarded to the Royal Museum 
from Stromstad, immediately after its capture. 
The chief characteristics of the older specimens are 
the comparatively short head c , the lower (more elongated) 
shape of the body d , the sometimes greater relative distance 
between the tip of the snout and the first dorsal fin'', the 
somewhat shorter ventral fins 7 and the somewhat shorter 
base of the anal fin 9 ’, while the lower lobe of the caudal 
fin seems to become shorter and shorter than the upper. 
a The breadth of the head behind (straight across the posterior part of the gill-cover) is about -/, of its length. From this point 
the body tapers evenly towards the caudal fin, the breadth (thickness) at the beginning of the first dorsal fin being about equal to or slightly 
greater than the least depth of the tail. 
h Cf., however, the above remarks on the variations of colour belonging to different localities. 
c In the specimens from Bohuslan belonging to the Royal Museum, between 267 and 416 mm. long, the relative length of the head 
decreases with increasing age from 2 3 ‘ 1 to 22 % of the length of the body minus the caudal fin, and the length of the head behind the eyes 
decreases in the same manner from 1 2 ' 2 to 1 1 ' 6 % of the latter length. 
(l The greatest depth of the body (at the beginning of the first dorsal fin) decreases in the manner just described from 21 1 ., to 19 1 /, 
°/o of the length of the body (from the tip of the snout to the end of the middle caudal rays); and the length of the head behind the eyes 
thus increases from 51'7 to 54’8 % of the greatest depth of the body. 
e This distance increases, in the above specimens, from about 44 to about 4 5 1 /., % of the length of the body or from about 69 to 
about 73 % of the distance between the anal fin and the tip of the snout, but proves to be somewhat greater in the males than in the fe- 
males. This change of growth is more distinctly shown in comparison with the length of the head, which decreases from 48 to 45 % of 
the distance between the first dorsal fin and the tip of the snout. 
■ r The relative length of these fins diminishes in the above specimens from 13'3 to 11 % of the length of the body or from aboiu 
86 1 o to about 74 / of the length of the pectoral fins. 
,J The length of the base of this fin diminishes in the above specimens from 10'1 to 8'8 % of the length of the body or from 100 
to about 90 % of the least depth of the tail. 
