384 Fleterogenetic Development in Diaptomus. (Api, | 
Diaptomus leptodus has not been recognized in the South 
Fig. 4 of Plate vii in the NATURALIST, July, 1882, represents the 
process or inner branch of fifth foot reversed, probably by pre 
sure; Fig. 6 of the same plate omits one of the seta on the lat | 
joint. Now comparing these figures with others, we see less dk 
ference than as given. : 
EPISCHURA‘FLUVIATILIS, sp. nov. (Figs. 10-20, Plate v). 
The genus Epischura, which was founded by S. A. Forbes l 
upon a species of Copepod, E. /acustris, inhabiting Lake Michigat, 
is one of the most interesting as well as anomalous of the = l 
of Calanidæ. The typical family likeness is preserved, but thereat 
several peculiarities which have no parallel in Copepoda, if e 
where. ; ; 3 
The animal for which the name Epischura fluviatilis is propose l 
is undoubtedly extremely near the above, but in several : 
disagrees with the points in Forbes’ description which he nye i 
to rely upon as of generic importance. It might be assot 
these differences have generic value, and I should be inclined © 
so regard them except that there seems a possibilty a 
Forbes has slightly mistaken the homologies of the ano 4 
organs as indicated below. x 
As no generic characters were given, this second species E 
warrant an attempt, as follows : i 
EPISCHURA Forbes, 1882. aa 
Char. gen.—Cephalothorax slender, 5-6-jointed ; abdomen 4-jointed a 
jointed in female; second antennæ as in Diaptomus ; mandibular palp < bot 
swimming feet all biramose; inner ramus 1-jointed; left foot of be gye 
or obsolete, right foot in female slender, last feet of male, greatly modified ott 
foot biramose, inner ramus short, lamellate, 1-jointed with claw-like — 
branch nearly like female, left foot coalesced with the first two joints of 
-extremity alone free; set of caudal stylets three. 
Forbes says of Æ. /acustris that the female has a proces 
the abdomen and in both sexes the latter is curved and iil 
In Æ. fluviatilis the abdomen of the female appeared i ý 
jointed, and differs in no way from Diaptomus except He | 
number of setz. It is to be remarked that Epischura offers wd | 
treme example of the tendency noticed in all Cope ip 
frequently in higher Crustacea, to diminish or abort Poe 
branch of biramose organs on either side the median lin® 
1S. A. Forbes. On some Entomostraca of Lake Michigan. AM “oil 
July, 1882, . 
