724 



FRESH-WATER BIOLOGY 



165 (164) Post-abdomen broader toward apex. Alona intermedia Sars 1862. 



Body evenly arched but not very high. Post-abdomen 

 long, broad, enlarged toward apex, with rounded angle; the 

 8-9 marginal denticles rather small and thick; the lateral 

 denticles or fascicles much more conspicuous, consisting of 

 bundles of fine setae. The distal seta in each bundle is the 

 largest and the size of setae increases toward apex of post- 

 abdomen. The distal bundles project beyond margin of 

 post-abdomen. Length, 9, ca. 0.4 mm. See Fig. 1129, g. 



Rare; specimens closely agreeing with Lilljeborg's descrip- 

 tion and figures found in Wisconsin. Possibly not Sars' inter- 

 mr.dia, as his figure of that species resembles some varieties 

 of Lilljeborg's reclangula. 



Fig. 



0.1 MM. ' 



1131. Alona intermedia. 



166(151) With oblique Striae Alonella karua 



Turn to the key at the number indicated where the species named is discussed. 



232 



167 (137) Rostrum broad, semicircular Graptoleberis Sars 1863. 



Sole species Graptoleberis iestudinaria (Fischer) 1848. 



Posterior margin with 2 strong teeth at 

 infero-posteal angle; valves and head with 

 conspicuous reticulation. Head large; 

 fornix very broad, forming a semicircular 

 rostrum, covering anteimules and extend- 

 ing down as far as ventral margin of 

 valves. Post-abdomen bent at the sharp 

 pre-anal angle; tapered toward claws, so 

 that form is nearly triangular; marginal 

 spines small; lateral fascicles minute, some- 

 times wanting. Claws small, with i mi- 

 nute basal spine, sometimes wanting (var. 

 inermis Birge) ; $ with long, slender post- 

 abdomen, without spines; vas deferens 

 opens on ventral side; claws very minute; 

 hook of first foot slender. 

 Length, 9, 0.5-0.7 mm.; $, 0.5 mm. or 



O.I MM. 1 1 



Fig. 1132. Graptoleberis iestudinaria. 



Color gray to yellow-white; sometimes opaque 

 less. 



Common among weeds or on bottom of pools and margin of lakes. 



168 (136) Rostrum considerably exceeding antennules. 



169 



169 (170) Post-abdomen with marginal denticles only. Alonella. 

 Turn to the key at the numbers indicated where two species are discussed. 



240, 241 



170 (169) Two to four marginal denticles; long series of lateral denticles. 



Rostrum very long, recurved. . . Rhynchotalona Norman 1903. 



Sole species Rhynchotalona falcata (Sars) 1861. 



General form of body like Alona. Ros- 

 trum very long, slender, and recurved 

 under the head. Post-abdomen stout, 

 thick, bent at anus, truncate at apex; 

 with_ about four rather stout marginal 

 denticles near apex, and a lateral series, 

 continued nearly to anus, of very fine 

 spinules in an unbroken row. Intestine 

 with cecum. $ (European) with long 

 rostrum, bilobed at apex; post-abdomen 

 tapering and armed with hairs only; ordi- 

 nary hook on first foot. Color yellow or 

 greenish. Length, 9, 0.5 mm.; J, 0.4mm. 



Maine, Michigan. 



0.1 MM. 



Fig. 1133. Rhynchotalona fakata. 



