902 
SCANDINAVIAN FISHES. 
mens — and deep-snouted ( hypselorhynchi ■“), or between 
narrow-snouted (, stenorliynclii 1 ) and broad-snouted ( eury - 
rhynclii 0 ), without these differences being always at- 
tended by analogous differences between dense gill- 
rakers ( pycnocentri d ) and scattered (: manocentri e ). To 
this we must add that among the comparatively pyc- 
nocentrous Gwyniads of Lake Wetter specimens occur 
(tig. 226) which differ in hardly any respect from the 
form of the manocentrous Gwyniads, e. g. in Lake Stor 
(tig. 225). An examination of the Lake Wener Gwyn- 
iads has yielded the same result; but in both these 
lakes, as well as in the sea and in the large rivers 
flowing into the sea, there appears a still more pro- 
minent alteration in the form of the snout, an alteration 
which has given rise to the name of ndbbsik ( Beaked 
Gwyniad, Houting; tig. 227), the oxyrhynchus of old 
writers. This alteration consists partly in the prolonga- 
tion and thickening of the ethmoidal cartilage, but 
mainly in an agglomeration of connective tissue and 
fat. It is analogous to the elongation of the point of 
the lower jaw in the Salmons, and cannot in itself 
justify any specific, distinction, whether it appears in 
the narrow-snouted Gwyniads 7 or in the broad-snouted 
Its reaches its highest development in old Gwyniads 
from the depths of Lake Wener, which do not differ, 
however, in other respects from their companions, the 
broad-snouted Gwyniads of the same lake. But the 
Houting form was first observed in the North Sea on 
the Belgian, Dutch, and German coasts, whence it ascends 
the Rhine, Weser, and Elbe in order to spawn, and in 
the south of the Baltic, where it enters the Haft’s and 
the Oder. 
However variable the shape of the snout may ap- 
pear, it is still the most trustworthy guide to the de- 
termination of the forms — as the fisherman’s experience 
has long since taught him — although the characters 
cannot be well defined. This indefiniteness of character 
we can easily understand, for we can range the diffe- 
rent forms in an almost unbroken series according to 
their varying degrees of resemblance to one or other 
of the above-mentioned extremes, the muksitn and the 
polcur. 
The shape of the snout also affects the length of 
the jaws, from which we may derive important cha- 
racters. The appearance of the form-series at once 
suggests that the pycnocentrous forms should have longer 
jaws, and the changes of growth 71 show that during 
youth the relative length of the jaws undergoes a re- 
duction. But in old Gwyniads from Lake Wener — the 
form which in Gunther bears the name of Ooregomis 
maxillaris, the German Madui-Mar cme — we observe 
a retrogression towards the characters of youth, a re- 
trogression which ranges this form, as regards the 
length of the maxillaries, even when the tip of the 
snout is prolongated to the Houting type {Cor. oxy- 
rhynchus), beside the pycnocentrous asp from Lapland. 
The other extreme of the series — the polcur form, 
which, as we have mentioned, really belongs to Siberia 
and Northern Russia, but also occurs in the northern- 
most rivers of Sweden — sometimes has the maxillaries 
so reduced that we have conferred on this modification 
the special name of brachymystax'. 
The shape of the bod)’ is the same as in the Ven- 
dace, but in general somewhat deeper, deepest as a 
rule in the polcur and the forms that come nearest it, 
the manocentrous forms as a rule having a deeper body 
than the pycnocentrous. The greatest depth of the 
body varies in adult Gwyniads between about 22 and 
25 % (in gravid females as much as 27 %) of its length; 
in the polcur the percentage is usually 26 or 27. In 
young Gwyniads measuring 37 — 143 mm. we find the 
greatest depth to increase with growth from 1 5 x / 2 to 
19 Vs of the length. But on account of the temporary 
variations due to the periodical tumidity of the gene- 
rative organs, the greatest depth of the body, here as 
in most cases, is ill adapted to express its characteristic 
form. Far more important in this respect is the least 
depth of the body. This is seldom so small as in the 
“ bynqloSi high. 
b ovevog, narrow. 
c Slqvq, broad. 
d From rcvvjvog , dense , and v.tvroov, spine. 
e yavog, scattered. 
f Smitt, 1. c.. lafl. IV, figg. 69 and 70. 
g 1. c., fig. 67. 
h 1. c., tab. metr. XIII, and */s > n Nos. 362 — 364 and 397 — 403. 
’• Answering in essential respects to a form which inhabits the depths of the Lake of Constance, and which has been named Core- 
gonus acronius. But this latter form', judging by the two specimens we have examined (see Smitt, 1. c., tab. metr. X, Nos. 162 and 163), 
has much longer pectoral and ventral fins and a shorter snout. 
