■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. A^alves 

 •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 setse. Valves marked by closely-set, conspicuous, 

 longitudinal strise, 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 sette ff^. The terminal setsE are of unequal 

 length. All are plumose and without spines. The eighth seta is of 

 moderate length, bi-artieulate and plumose. Spines of antenuce \^. 

 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 squamte. Terminal claws 

 smooth. Basal spine rather large. Abdominal setce of ordinary 

 length. Length 0.8 mm.; male 06 mm. Obviously this species is near 

 to A. elegans. 



Alona lacustris Daday. 



Daday '88. 



"Rostro brevi; macula cerebral! oculo minore; labro 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. fern., 

 ■0.4-0.5 mm.; altit. 0.35-0.4 mm." 



It is questionable whether this form is sufficiently differentiated 

 from A. jiorvnla; it is also very like A. guitata=A. intermedia. 



Alona tenuicaudis Sars. 



Plate LXII, Fig. 11. 



Alono camptocercoides — Schoedler. 



Form nearly rectangular; ventral margin rounded, with long setaj, 

 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. 



