122 Part ITT.—Twenty-fourth Annual Report 
In respect to the Girth, a character in which there is a wide difference 
existing among the three species, so far as the eye can judge, we find a 
distinct enough separation between certain of the species. At the 
pectoral region Juscus has a girth equal on the average to 60 per cent. of 
the length of the fish, thus exceeding by a considerable amount the 
respective girth in minutus and esmarkii. And since the range of 
variation in /wscus does not overlap that of esmarkiz the difference in the 
girth is of some specific value. The ranges of variation in /useus and 
minutus meet though they do not overlap, and between these two the 
character is of more or less negative value. Minutus and esmarki 
overlap in their ranges of variation and this character is not therefore of 
value. At the anus, the girths in the three species increase a little. The 
girth of minutus now overlaps that of duscws. In the girth at the root of 
the tail, where a considerable difference exists between minutus and 
luscus, judging by the eye, a small difference only is shown by the per- 
centages, but a complete separation is seen between luscus and esmarkit 
in respect to this character. ‘The dorso-ventral height of the body agrees 
closely with the girth relations. 
In all three species the horizontal diameter of the eye is on the 
average as great or greater than the length of the snout, z.e., the distance 
from the tip of the jaws to the anterior edge of the orbit. Luscus 
has a distinctly smaller eye than minutus and esmarkii—which two 
agree exactly—but complete separation in this character does not 
hold between any two of the species. In the size of the interorbital 
space the reverse relation is seen, Zwscws having a larger average than the 
other two, in which there is equality. By their variation, however, they 
merge into one another. 
In the matter of the lengths of the ventral, pectoral, and first dorsal 
fins, although very distinct agreements and differences are shown in the 
averages, still the latter are so small that they are really of no specific 
value. Thus in minutus and esmarkzi the average size of the ventral fin 
is the same, while that of duscus is a little larger; whereas in the case of 
the pectoral fin, /wscus and esmarkii agree closely and have a fin a little 
longer than minutus. The first dorsal fin is on the average rather larger 
in luscus than in minutus, but the two ranges of variation overlap. 
This character was not noted in esmarkit. 
In the following characters—height of the lateral line above the lateral 
axis, the length of the rami of the tail, and the spread of the tail, the 
greatest height of the unpaired fins—only a few observations were made. 
Luscus shows a considerably higher bend in the lateral line than 
esmarkit, and a little higher than minutus. 
The lengths of the rami of the tail of the three forms agree closely, but 
in the spread of the tail Jwscus and minutus exceed esmarkii, being on the 
average half as broad again as the latter. 
The length of the barbel was in esmarkit on the average 3 per cent. of 
the length of the fish ; in one specimen of mdnutus the barbel was 5 per 
cent. of the same quantity. 
Distances from the Anterior Tip of the Body.—The average for the 
length of the snout, 7.e., the distance of the anterior border of the orbit 
from the tip of the jaws, is the same in luscus and minutus, and 1 per 
cent. over that in esmarkiz; but in the latter the snout is measured from - 
the tip of the mandible, which projects on the average 1 per cent. in front 
of the premaxilla. When that amount is subtracted we get an equal 
average measurement for the snout in all three. 
The ventral fin is situated nearest the tip,of the jaws in /wscus, next in 
minutus, aud farthest back in esmarki/. The ranges of variation of the 
