BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 24, AFD. IV. N:0 8. 15 
can attribute to this difference in the length of a fin-ray. 
I shall return to this question a little later in connection 
with a discussion of the different measurements and the con- 
sequences of these. 
In addition to the characters noticed above, which are 
all mentioned by HEcKEL, other writers on this subject, who 
distinguish between the species, have introduced some new 
ones. Thus GÖNTHER in the »Catalogue of Fishes> gives, be- 
side some of HecKer's, the following new characters. The 
lateral line in OC. gobio runs fairly straight along the middle 
of the body and ends in the middle of the caudal-base, while 
in OC. poecilopus it runs above the middle of the body and ends 
at the posterior part of the second dorsal fin. Moreover, the 
vent in CO. gobio is situated rather nearer the tip of the snout 
than the end of the tail, while in C. poecilopus it lies midway 
between the tip of the snout and the base of the caudal fin. 
The different course of the lateral line. 
This character is employed by LILLJEBORG, who also 
mentions it in his specific diagnoses, so far as concerns 
the different length of the lateral line. Professor SMITT men- 
tions this difference only and I may be allowed to quote 
his own words on this subject: »The lateral line in C. 
poecilopus is always found imperfect, or at least its open- 
ings and pores become indistinct at the middle of the second 
dorsal fin and sometimes just behind the beginning of this 
fin, but its usual course to the base of the caudal fin is 
generally indicated by a groove in the skin. In this re- 
spect, however, C. poecilopus does not stand alone. The 
posterior part of the lateral line is indistincet and ap- 
parently destitute of pores — — — occasionally in C. gobio, 
where, however, it is generally perfect or perhaps becomes 
indistinct for a small part of its course, to be again con- 
tinued by distinct pores farther back» — In C. poecilopus 
the posterior portion of the lateral line is usually totally 
wanting, and if it happen to exist it is only as a narrow 
groove without pores, which is distinetly curved at the end 
of the second dorsal, while in C. gobio only exceptionally is 
the posterior part of the lateral line found to be indistinct. 
If it be difficult to trace the porous openings as far as to 
