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 sets. Valves marked by closely-set, conspicuous, 
longitudinal strix, 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 sete 32°. The terminal setz 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 0.6mm. 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. 
