242 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
* Alona lepida Birge. 
General shape of the genus. Head depressed, rostrum sub-acute, 
nearly reaching the level of the ventral margin of the shell. Valves 
quadrangular, dorsal margin arched, caudo-dorsal angle obtuse, well 
marked. Caudal margin oblique, bearing a row of spinules. Caudo- 
ventral angle rounded, very slightly emarginate. Ventral margin 
with plumose sete. Valves marked by closely-set, conspicuous, 
longitudinal strice, alternately stronger and weaker, occasionally anas- 
tomosing, parallel to the dorsal and ventral margins and converging 
to a reticulated area at the cephalo-ventral portion of the valves. 
The antennules extend nearly to the end of the beak, are small, spin- 
dle-shaped. Antennary setze 32°. The terminal sete are of unequal 
length. All are plumose and without spines. The eighth seta is of 
moderate length, bi-articulate and plumose. Spines of antennze 4}. 
Eye moderate. Macula about as large as eye, angular, and somewhat 
nearer to eye than to apex of rostrum. Post-abdomen enlarged pos- 
teriorly, lower angle rounded, bearing 15 to 17 serrate post-anal den- 
ticles and about the same number of squame. ‘Terminal claws 
smooth. Basal spine rather large. Abdominal sete of ordinary 
length. Length0.8 mm.; male 0.6 mm. Obviously this species is near 
to A. elegans. 
Alona lacustris Daday. 
Daday ’88. 
“‘Rostro brevi; macula cerebrali oculo minore; Jabro processu mediali glabro; 
testa corporis striis longitudinalis dense vestita, linea dorsali parum arcuata, margine 
ventrali subrecto, setas postice breviores gerenti, postice angulum obtusum inermem 
formanti; cauda brevi, apicem versus rotundatum attenuata serie fere marginali 
aculeorum sensim minorum armata, unguibus caudalibus unidentatis. Longit. fem., 
0.4-0.5 mm.; altit. 0.35-0.4 mm.’’ 
It is questionable whether this form is sufficiently differentiated 
from A. parvula; it is also very like A. guttata=A. intermedia. 
Alona tenuicaudis Sars. 
PLATE LXII, Fie. 11. 
Alono camptocercoides—Schoedler. 
Form nearly rectangular; ventral margin rounded, with long sete, 
posterior angle rounded. Beak short, pigment fleck smaller than the 
eye. Post-abdomen with sides parallel, long, incised below; lower 
angle armed with about six strong teeth, remainder of the series small; 
a lateral line of scales present; claws with a strong basal spine. The 
shell is striate with longitudinal lines. Length 0.5 mm. 
One of the most easily recognized species; not identified in 
America. 
dl « 
