THE CYPRINOIDS OF CENTRAL NEW JERSEY. 327 
varieties that, seen from an evolution standpoint, are well ad- 
vanced to that point, where the ‘‘species” commences and the 
“variety” ends. To some of these instances, we will call partic- 
ular attention elsewhere, and remark here that, besides the twelve 
species given by Cope, there are included four well marked species, 
of genera not included in the list referred to, being Hybognathus* 
Agassiz, Albernellus Girard, and Hyborhynchus Agassiz, these 
making the number of genera, nine, that are represented in the 
Delaware fauna. 
So far as our investigations have enabled us to determine, the 
cyprinoids of the Delaware River, at the head of tide water, and 
in the neighboring streams, are as follows :— 
1. Semotilus rhotheus Cope. “Chub.” This is our largest and, 
in the river, our most abundant species. Although the males, in 
spring, are then most highly colored, they do not become at any 
season dull or leaden tinted. We have noticed that the variety of 
tints and general ruddy tinge of the whole fish vary considerably, 
in different streams; the milky, turbid waters of clay creeks ap- 
pearing to have the effect of keeping down the rich colors that 
make this fish so beautiful from March to J une, when found in the ` 
river or clear spring brooks. Some peculiarities of its coloring 
fade almost immediately, and others change in hue, on taking the 
fish from the water. The first published description of this fish, 
detailed the colors of a living specimen, which accounts, we sup- 
pose, for the difference in the general appearance as given by us, 
and as noticed by Prof. Cope, t when examining dead specimens. 
The largest specimen we have met with weighed 1 Ib. 14 oz. 
‘2. Semotilus corporalis (Mitchill). This “chub” is also an in- 
habitant of several little brooks, sometimes reaching considerable 
size, but never attaining the dimensions of S. rhotheus. As we 
have often noticed with reference to allied species of fishes, so in 
this instance ; we do not find them i. e., the two species of Semo- 
tilus associated in small streams, nor intimately so, in the river, — 
Besides the marked difference in color, the smaller scales at, once 
make evident the great difference between this and the preceding ; 
which is much more nearly allied to the northern Semotilus argen- 
teus Putnam (Leucosomus pulchellus Girard, et auct.) ‘In Gun- 
* Synopsis of fishes of North Carolina: Proc. Amer. Philos. Soc., vol. ii, p. 466. 
t Proc. Acad. Nat. Sci., Phila., 1861, p. 154. fl. c. p. 564. : 
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