4 ANDERSSON, COMPARISON OF COTTUS POECILOPUS WITH COTTUS GOBIO. 
remarked above, HECKEL considers it a distinct species, but 
this opinion is opposed by GÖNTHER in his paper on »>Die 
Fische des Neckarss. He gives it as his own opinion, that 
both C. poecilopus and two other forms from the fresh waters 
of Europe, decided by HECcKEL to be distinct species, are only 
local forms of C. gobio L., and also that each of these forms 
is characteristic of some particular places, where no other 
form of this fish is ever found. At a later period GÖNTHER 
changes his opinion on finding C. poecilopus as a more decided 
form than either of the other above-mentioned local forms, 
for which reason he in his »Catalogue of Fishes>, published 
1860, defines C. poecilopus as a distinct species, different from 
C. gobio, which latter then he considers as including the 
other forms mentioned as separate species by HecKzEL. L. H. 
JEITTELES arrives at the same conclusion, revising in his paper 
sUber die Siisswasserarten der Fisch-Gattung Cottus> the opi- 
nions previously held by writers on the subject with regard 
to the European fresh-water forms. 'PThe German authors 
MöBirvs & HEINCKE and BENECKE suggest that C. poecilopus 
is only a variety of C. gobio. These authors evidently have 
not had any specimens of C. poecilopus to examine; nor has 
the Swiss Fartro, who is very doubtful because there are no 
definite statements as to the uniform observation of charac- 
ters. Dar simply regards C. poecilopus as synonymous with 
C. gobio and tells us he had examined a specimen which 
proved to be a distinct intermediate form between the two 
species; but in his description of this intermediate form we find 
nothing to show that it is not a true C. gobio. He defines the 
specific characters, judging only by the length of the pectoral 
and ventral fins, the branching of their rays, and by the 
different position of the vent, all of them characters that 
"vary considerably in both species. Moreover he says that the 
lateral line runs fairly straight along the middle of the body, 
which is a comparatively constant character of the C. gobio. 
Of our Scandinavian authors who have had opportunity 
for examining both species, NILSSON, LILLJEBORG, and COLLETT 
unhesitatingly pronounce C. poecilopus to be a separate spe- 
cies, while MaLMm and SMITT leave the question open. 
From the preceding short account it is clear that a closer 
study of the relationship between C. poecilopus and C. gobio is 
perfectly warranted, and it is on the suggestion of Professor 
