406 
SCANDINAVIAN FISHES. 
two other groups, but in the differentiation of its forms 
is so little advanced that both these varieties may also 
be ranged as intermediate forms between two species 
of one of the other groups". The first group must, 
therefore, stand nearest the presumable original type 
of all three groups, unless, indeed, it may be shown 
that it is that original type. 
When Lilljeborg first discovered his Platessa clvi- 
nensis , he suspected that it was identical in species with 
Pallas’s Pleuronectes cicatricosus / and in this suspicion 
he was undoubtedly right. In another passage 6 we have 
combined this species with Stokers Platessa glabra; but 
the collections of the Vega Expedition prevent us from 
following Jordan and Gilbert’s example", and unre- 
servedly uniting into one single species the two species 
described by Pallas, PI. glacialis and PI. cicatricosus. 
Pallas based his distinction between these species chiefly 
on the deeper form of the body and the closer seal}' 
covering of Pleuronectes glacialis. This difference re- 
appears, even though it is modified by differences of 
age and sex, between the specimens of PI. glacialis 
brought home by Nordenskiold’s Expedition of 1875 
from Chabarowa and by the Vega Expedition from 
Najtschkaj (N.E. Siberia) and the numerous examples 
of PI. cicatricosus brought home by Lieutenant Sande- 
berg from Archangel. According to these collections 
the following distinctions are valid: 
PI. glacialis 
fr. Najtschkaj. 
Greatest depth of the body. in % of the length of the body > 41 (Average: 43.9) 
Length of the head in % of the greatest depth of the body < 57'' (Average: 51.5) 
Postorbital length of the head in % of the greatest depth of the body < 38 (Average: 35.5) 
Length of the head in % of the greatest distance between the lateral line and the ventral edge < 93'' (Average: 86.3) 
PI. cicatricosus 
fr. Archangel. 
< 41 (Average: 39.2) 
> 57'' (Average: 61.7) 
> 40'' (Average: 42.5) 
> 93 (Average: 101.6) 
Although these differences are not great, and al- 
though, considering the variability of the kindred spe- 
cies, they seem rather to belong to varieties, still they 
exist, to judge by 9 specimens of PI. glacialis and more 
than 20 of PI. cicatricosus: and so long as a character 
proyes tenable, we have no right to reject the distinc- 
tion based on it, whether we choose to regard the latter 
as a distinction of species or merely of variety. As is 
generally the case in the Scandinavian Flatfishes, the 
females are in the majority, and this to such an extent 
that we have not found a single male among the spe- 
cimens of PI. cicatricosus. However, this does not af- 
fect the significance of the differences given here, as 
it is by the shallower (narrower) form of the body 
that the males are externally distinguished, and in PI. 
cicatricosus they would thus only have still further di- 
minished the average depth of the body. 
Pallas obtained his Pleuronectes cicatricosus from 
the basin of the Pacific" and PI. glacialis from Kara 
Sea and the Gulf of Obi '; and it would thus appear 
that the former belonged to the east, the lattbr to the 
west, of the Arctic Ocean and the Old World. But 
we have no recorded observation of PI. glacialis west 
of Nova Zembla, while PL cicatricosus , on the other 
hand, must be recognised as common in the White Sea. 
According to Gunther’s description 5 ' of the type-spe- 
cimen of Richardson’s PI. glacialis , from Bathurst Inlet 
(the middle of the Arctic coast of North America) this 
specimen really belongs to the form thus entitled by 
Pallas. On the other hand, the Alaskan species de- 
scribed under this name by Jordan and Gilbert and 
figured by Todd 7 ', evidently possesses the characters of 
PI. cicatricosus , of the occurrence of which on the Arctic 
coast of North America east of Alaska we have no re- 
corded observation, though it is common and known by 
the name of Christmas-fish at Salem, on the Atlantic 
coast of the United States. The latter species is just 
as little known to the north of Asia, west of Behring 
Strait. In its geographical range there thus appear, as 
far as we know at present, three great gaps, the first 
a Lilljeborg also says of his Platessa dvinensis: ‘‘It seems to be an intermediate form between Plat, vulgaris and Plat, jlesits. By 
the structure of the teeth it is approximated to the former, and by the covering of the body and the coloration to the latter.” 
1 Ur var tids forslcning (Retzius), No. 29, p. 59. 
c Bull. U. S. Nat. Mns., No. 16, p. 837. 
d An exceptional case. 
e “Specimina e mari inter Camtschatcam et Americana lecta mihi retulit D. D. Mere.” 
f “In littoribus vadosis maris glacialis ad Sinum Carensem et Obi fl. ostia legit Basil Sujef.” Chabarowa, where Nordensici6ld’s Ex- 
pedition of 1875 found PI. glacialis , lies off Jugor-scharr, just at the division between Kara Sea and the Murman Sea. 
9 Brit. Plus. Cat., Fish., vol IV, p. 442; Pleuronectes Franklinii. 
h Br. Goode, Fish., Fish. Industr. U. S., sect. I, pi. 47. 
