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. 11 29, g. 

 Rare; specimens closely agreeing with Lilljeborg's descrip- 

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



' media, as his figure of that species resembles some varieties 



Fig. 1 13 1. Alona intermedia. of Lilljeborg's rectangula. 



166(151) With oblique striae Alonella karua . . 232 



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



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



Sole species Graptoleberis testudinaria (Fischer) 1848. 



__^^^ ^>.jytu.- a n m. <uB t im,,^,^,^^ Posterior margin with 2 strong teeth at 



^^^ ^ ' ^^.7^-^^^**^%^ infero-posteal angle; valves and head with 



y'"^ "~ <*" '^ ^^^Ssv conspicuous reticulation. Head large; 



j^ " j::^ \^bv fornix very broad, forming a semicircular 



M^, . , - •■ '^^^ rostrum, covering antennules and extend- 



y^' ' " • " ^ ^"-"^-^ ^^^ down as far as ventral margin of 



£/^ . ,^«=^j, "^4 valves. Post-abdomen bent at the sharp 



ff^^ K ■^-»s?^?l'^^-^W \ pre-anal angle; tapered toward claws, so 



/'Q^^^j-'^ '~ :.^ ' jz^~ ^ that form is nearly triangular; marginal 



^^^'^ y *^ ^ V^ spines small; lateral fascicles minute, some- 



^ V^Ll , -^ ^ ^ JJ,^'-^ times wanting. Claws small, with i mi- 



TS^\r\™\^\tHWN\rTn^\^^^'^ ^n ^"^^ ^^s^' SP'^^' sometimes wanting (var. 



\WM\ ,m\i#W \\ \^\^^\^ ^^ N.-^ ^-^^^^.^ Bjrgg). ^ ^j^i^ iQj^g^ gignder post- 



0.1 MM- - \ i i abdomen, without spines; vas deferens 



Fig. 1 132. Graptoleberis testudinaria. opens on ventral side; claws very minute; 



hook of first foot slender. 

 Color gray to yellow-white; sometimes opaque. Length, 9- o-5-o.7 mm.; J, 0.5 mm. or 

 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. . 240, 241 

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



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



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

 Sole species Rhynchotalona falcata (Sslts) 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 



tf#7 -/ -" iV ^\ 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 

 0.1 MM. - greenish. Length, 9 , 0.5 nmi.; ^ ,0.4 mm. 



F1G.1133. Rhynchotalona falcata. Maine, Michigan. 



