ROTATORIA OF THE UNITED STATES. 
85 
Body very short and broad, oval in dorsal or ventral view. Head much narrower than body, 
tapering to the obliquely truncate corona, composed of a single wreath of cilia. Body truncate 
behind; from the lower side of the truncate surface rises the single joint forming the short foot. The 
two tapering toes are about as long as the body is thick at the posterior end; they stand some dis- 
tance apart at base. The internal anatomy offers nothing especially noticeable save the lack of an 
eye, which is of course the character that places this form in the genus Pleurotrocha. Length, 110/4. 
Animal ectoparasitic on the annelid Nais lacustris. 
Pool near Lake St. Clair (Jennings, ’94, under the name Pleurotrocha constricta Ehr. ). 
NOTOMMATA Gosse. 
30. N. aurita Ehrenberg. 
Rare, among plants on bottom of Put-in Bay Harbor, Lake Erie. 
Lake St. Clair (Jennings, ’94). Sandusky Bay, Lake Erie (Kellicott, ’96). Waters connected 
with the Illinois River at Havana, 111. (Hempel, ’98). 
31. N. tripus Ehrenberg. 
East Harbor, Lake Erie, in Utricularia. 
Shiawassee River at Corunna, Mich. (Kellicott, ’88). Lake St. Clair and White Lake, Muskegon 
County, Mich. (Jennings, ’94). Trenton, N. J. (Stokes, ’966, under name N. mirabilis n. sp.). Waters 
connected with the Illinois River at Havana, 111. (Hempel, ’98). Brook, Hanover, N. H. (PI. S. J.). 
32. N. truncata Jennings. 
In Naias and Chara, bottom of Put-in Bay Harbor, Lake Erie. 
Lake St. Clair (Jennings, ’94). This species has recently been found by Stenroos (’98) in Finland. 
W. 6 racliyota Ehrenberg. — Lake St. Clair (Jennings, ’94). 
N. collaris Ehrenberg. — Lake St. Clair (Jennings, ’94). 
iV. torulosa Duj. — Lake St. Clair and Chippewa Lake, Mecosta County, Mich. (.Jennings, ’94). 
JV. monopus Jennings. — Lake St. Clair (Jennings, ’94). Lake Michigan, Round Lake, Pine Lake, 
West Twin Lake, and Susan Lake, near Charlevoix, Mich. (Jennings, ’96). 
N. vorax Stokes. — Trenton, N. J. (Stokes, ’97). Sandusky Bay, Lake Erie (Kellicott, ’97). 
W. cyrtopus Gosse. — Waters connected with the Illinois River at Havana, 111. (Hempel, ’98). 
N. mirabilis Stokes. —N. tripus Ehr. 
N. lacinulaia Ehrenberg., see Diaschiza lacinulata Ehrenberg. 
COPEUS Gosse. 
33. C. pacliyurus Gosse. 
Bottom of shallow parts of Lako Erie near Put-in Bay. 
Tamarack swamp on the shore of Pine Lake, near Charlevoix, Mich. (Jennings, ’96). Reservoir of 
the water supply, Hanover, N. H. (H. S. J.). 
C. labiatus Gosse. — Shiawassee River at Corunna, Mich. (Kellicott, ’88). Lake St. Clair (Jennings, 
'94). Pine Lake, near Charlevoix, Mich. (Jennings, ’96). Brook, Hanover, N. H. (H. S. J.). 
C. ehrenbergii Gosse. — Sandusky Bay, Lake Erie (Kellicott, ’97). 
C. cerberus Gosse. — Lake St.Clair and the following inland lakes of Michigan: McLaren Lake, 
Oceana County; Crooked Lake, Newaygo County; Chippewa Lake, Mecosta County (Jennings, ’94). 
Sandusky Bay, Lake Erie (Kellicott, ’96). 
C. quinquelobatus Stokes. — Trenton, N. J. (Stokes, 96c). I have found a Copeus at Hanover, N. H , 
having five lobes to the brain, but agreeing in every other particular with C. pacliyurus ; this also 
seems true of Stokes’s 0. quinquelobatus. But the specimens at Hanover occurred along with typical 
specimens of 0. pacliyurus, having but three lobes to the brain ; moreover, the specimens with five lobes 
were a little larger than those with three lobes. I can not but think it probable that C. pacliyurus 
develops another pair of lateral lobes on the brain as it becomes larger, and that the species quinquelo- 
batus is founded on such specimens. This is rendered the more probable by the fact that in the speci- 
mens seen the development of the two lateral lobes varied greatly. 
C. americanus Pell. — Locality not given by describer, but probably Highland Falls, N. Y. (Pell, ’90). 
PROALES Gosse. 
34. P. sordida Gosse. 
Bottom of Put-in Bay Harbor, Lake Erie. 
Lake St. Clair (Jennings, ’94). Sandusky Bay, Lake Erie (Kellicott, ’96). 
P. fells Ehrenberg. — Lake St. Clair (Jennings, ’94). 
