lo4 DooUttle — New Cladocera from New England. 



Lake and Thomas Pond, ]\Iaine, Jnly-Angust, lOOG, 1907, 190S. TJare in 

 weedy, shallow margins or coves of lakes. 



Description. — Female. Oval, evenly rounded anteriorly, dorsal and 

 ventral margins approaching each other and produced posteriorly, tube- 

 like. Dorso-posterior angle acute hut not spined; ventro-posterior angle 

 sharp or rounded. Posterior margin low, i to y^ height, spinulose. 



Keel low, continuous; cervical sinus well developed. Sides of test 

 longitudinally concave from cervical sinus X the length of the body; 

 upper and lower margins of concavity thickened and ridged. Fornix 

 broad, horizontal limb with sides parallel, curving upward over antennae 

 and eye, and the vertical limb abruptly curving downward to near end of 

 rostrum. Antennules ten times as long as thick; lateral seta J4 from 

 base; six short olfactory setae, two four times their length and one five 

 times as long; the last nearly equalling the antennule; otlierwise armed 

 with very minute denticles and spinules only. Antennae not strong, 

 setae and rami equal, reaching to posterior third. Labrum with fenes- 

 trum of size and position to tit the grinding surface of the mandibles. 

 JNIaxillae with three teeth, the distal sparsely ciliated. Feet very much 

 like Ophryoxus. Postabdomen long, tapering to a jtoint, dorsal and 

 ventral margins both irregularly sinuous. The dorsal or anal margin 

 armed with eight to eleven minute spinules distally. Claw )^ the length 

 of the postabdomen, evenly and slightly curved, with two basal teeth, the 

 proximal smaller. 



Male. Immature males only have been found, resembling immature 

 females in their greater irregularity of outline, and in other general 

 features, save the antennal fonnula for setae, which are live on the 

 dorsal ramus, a seta being on each of the second and third segments, 

 additional to the three on the distal segment (VoV)- 



Measurements. — Egg bearing female from Anonymous Pond, Maine, 

 September 5, 1908. Length 1.14 mm. ; height .82 mm. ; posterior height 

 . 12 mm. 



Family CHYDORIDAE Leach (LYNCEIDAE Baird). 

 Chydorus bicornutus sp. nov. 



Type — To be dejjosited in tlu' I". S. National ]\Iuseum, from Sebago 

 ]>ake, Maine. Collected in Umbagog Lake, July-August, 1905, Maine 

 and New Hami)shire; Sebago Lake, Songo River, Panther Pond, Maine, 

 July-August, 190(), 1907, 1908. Found in small numbers in weedy margins 

 and coves of lakes and lagoon-like arms of rivers. 



Description. Female. — Shape of body or test proper from side view, 

 rounded with ventral margin sharply ventricose; from above broadly 

 oval, from the front broadly oval, but sides concave dorsally. 



The entire exoskeleton supports a most remarkal)le development of 

 horns and ridges and cells, somewhat as follows: From each valve of 

 the test there stands out a great horizontal horn , curving slightly posteri- 

 orly, often half the width of the l)ody proper. From this horn there run 

 two high ridges forward, and also two ridges over the back from horn to 



