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78 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
outer ramus of the fifch feet of the female obsolescent, inner ramus 
one-jointed, longer than the basai joint of the outer ramus. The fig- 
ures of the male feet are imperfect, but indicate small one-jointed in- 
ternal rami on both sides. 1.6 to 1.4 mm. long. 
Diaptomus amblyodon Marenzeller. 
PLATE IX, Fie. 2. 
Marenzeller ’73; Kortchaguine ’73 and ’87 (D. bogdanowi); De Guerne and Richard ’89. 
A large species very nearly allied to D. gracilis (4.0 to 4.5 mi. 
long). Last segment of the thorax ornamented with two spines. 
First abdominal segment with a conical process on either side armed 
with a long spine. Antenne extending to the end of the thorax. 
Last segment of the outer ramus of the fifth foot of the female well de- 
veloped, inner ramus one jointed, equaling the basal joint of the outer 
ramus and bearing three set; the claw strongly toothed. Inner rami 
of the male fifth foot one-jointed, short, unarmed. The basal joint of 
the outer ramus of the right leg with a small lobe. Apical segment 
of the left leg densely spiny, with two larger spines. 
We receive too late to enter the above list in the appropriate 
places descriptions of two species of Diaptomus by Professor Marsh 
(94). The descriptions are given verbatim with a reduced repro- 
duction of the figures. 
* Diaptomus mississippiensis Marsh. 
PLATE XLVII, Fias. 1-3. 
“‘Of moderate size. The first two segments of the cephalothorax 
are nearly equal in length, and together form somewhat less than half 
the cephalothorax. The last segment of the cephalothorax is armed 
behind with two minute spines. 
‘The first segment of the abdomen of the female is as long as the 
remainder of the abdomen and the furea; it is dilated laterally and in 
front, and bears two prominent lateral spines, theright spine being con- 
siderably larger than the left. The second segment is somewhat shorter 
than the third, and the third and the furea are of about equal length. 
‘‘The antenne reach beyond the farca. The right antenna of the 
male is swollen anterior to the geniculating joint, and the antepenul- 
timate joint is without armature. 
‘‘The outer ramus of the fifth foot of the female is two-jointed, the 
third joint being represented by two spines. The inner ramus is one- 
jointed, a little longer than the first joint of the outer ramus, and 
armed at the tip with minute sete and two rather long spines. 
‘‘Tn the right fifth foot of the male the basal joint is dilated on the 
inner margin. The first joint of the outer ramus is slightly broader 
than long. The second joint is elongated, quadrangular, with the 
