244 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
rows of tubercles. Sometimes a transition from a lined shell to a 
tuberculate shell is seen (as in Plate LXII, Fig. 14). Alona tuberculata 
Kurz is said to have a truncate and incised post-abdomen with no 
lateral row of hairs. Birge thinks these identical; if so, our form re- _ 
ferred to A. glacialis is identical with A. parvula. There is also a form 
found with the above in which no markings are visible and the shell 
is considerably arched; these were, however, nearly all ephippia 
females or approaching that period. 
**¢ Alona glacialis (?) var. tuberculata Herrick (Plate LXIII, Figs. 4-7 
and 14) will, then, be our tuberculated alona with a lateral row of scales 
and a series of fine spines along the anus. Alona glacialis (2) var. levis 
Herrick is the smooth form with higher dorsal margin. 
“The antenne of the two last have spines at the end of the rami of 
the antenne, a circlet of spines on the outside of the second joint of 
the setose ramus, and a spine on the basal joint of the other ramus; 
two of the sets at the end of the setose ramus have spines at the 
angles. The males found among the above small forms have the same 
_characters as var. levis and the abdomen is rounded at the end; the 
claw is situated in the middle of the lower margin, in front being the 
- opening of the porus genitalis and behind a cluster of hairs; the spines 
are absent, but there is a lateral row of long bristles. A strong hook 
is found on the first foot. Length 0.3 mm.’’ 
To the above, which expressed my opinion in 1884, I can only add 
that I am more than ever convinced that all should be united (probably 
with A. guttata). 
Alona dentata P. E. Mueller. 
PLATE LXII, Fias. 12, 13. 
Form sub-rectangular, somewhat arched above, obscurely longi- 
tudinally striated; lower angle obtuse, margined below with short 
setze. Post-abdomen small, slender, armed with a lateral line of scales 
and two strong teeth at the lower angle; claw with a minute basal 
spine. The form of the post-abdomen is identical with Harporhynchus 
falcatus Sars, which this species also resembles in having the pigment 
fleck larger than the eye, and in general form and the character of the 
striation. The beak, however, is very short. In size P. E. Mueller 
says it is among the smallest of the genus. 
Alona intermedia Sars. 
PLATE LXII, Fie. 15. 
Alona guttata—P. E. Mueller. 
Form sub-rectangular, rounded below; beak short; shell marked 
by longitudinal lines, which may be broken into indistinct rectangular 
