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176 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
*Scapholeberis aurita Fischer. 
Daphnia aurita—Fischer. 
Scapholeberis nasuta— Birge. 
Form much as in the last, head shorter, ‘‘ prolonged into a rather 
sharp beak, at whose apex the continuations of the fornices unite. 
The beak does not project downward as in S. mucronata, but back ward, 
and in its natural position lies between the valves.’’ The usual reticu- 
lated and lined areas are present and the balance of the shell is covered 
with ‘‘small pointed projections.’”’ ‘‘The antennules are much larger 
than in S. mucronata, though they do not project beyond the rostrum.”? 
The pigment fleck is long and large; the post-abdomen is much as in 
the preceding species; the terminal claws have several fine teeth. 
The males have the opening of the vas deferens close behind the 
terminal claws; mucro short and blunt, length 1.0 mm. This species 
is very near the next, but differs in several particulars. It forms the 
transition to the next, which is the extreme of the genus in a direction 
converse to that pursued by the S. armata. 
* Scapholeberis angulata Herrick. 
PLATES XLII, Fias. 9, 9a; XLV, Fias. 7, 7a. 
Herrick ’83. 
Form as in the above, but comparatively larger; valves quadran- 
gular, anterior margin strongly arched; head short, only slightly con- 
cave below the eyes; the beak is as in S. nasuta, but seems to be directed 
more nearly directly downward than in that species. The antennules 
are long and resemble those of Simocephalus. The pigment fleck is 
square and rather large; the antenne are of the usual size. The re- 
ticulated areas are as in the other spesies. The post-abdomen is more 
as in Daphnia, not so squarely truncate and with five to seven large 
teeth; the first foot has one elongated jointed seta; the posterior angle 
of the shell has no spine, at most there is a somewhat prominent acute 
_angle, the inner shell layer is armed at this point with some elongated 
teeth as in the corresponding situation in Simocephalus. On the whole, 
there is a similarity to that genus in this as well as in the previous 
species. S. nasuta has a short spine and elongated pigment fleck, the 
present species has a squarish but rather large fleck and no spine; the 
post-abdomen has a greater number of spines than any other species. 
South of Tennessee river, in Alabama and Mississippi. 
The species of this genus are predominatingly American, four out 
five being found in the United States; the fifth, moreover, is more 
often regarded a variety of one of the others; in fact, the absence of 
