ROTATORIA OF THE UNITED STATES. 
77 
O. crystallinus Ehrenberg. — Shiawassee River at Corunna, Mich. (Kellicott, ’88). Sandusky Bay, 
Lake Erie (Kellicott, ’96). 
O.umbella Hudson. — Sandusky Bay, Lake Erie (Kellicott, ’97). 
0. intermedins Davis. — Waters connected with the Illinois River at Havana, 111. (Hempel, ’98). 
Lacinularia socialis Ehr. — Exhibited in New York (Balen, ’85; Damon, ’86 and ’88). Shiawassee 
River at Corunna, Mich. (Kellicott, ’88). Pond near Norris Pass, on the Shoshone Trail, Yellowstone 
Park (Forbes, ’93). Saudusky Bay, Lake Erie (Kellicott, ’96). West Twin Lake near Charlevoix, 
Mich. (Jennings, ’96). Much less common than Megalotroclia alboflaricans. It seems probable that the 
latter is often mistaken for it. 
MEGALOTROCHA Ehrenberg. 
7. M. alboflavicans Ehrenberg. 
Very abundant on Chara in East Swamp, South Bass Island. 
Along shore of Niagara River (Mills, ’81, under name M.flavicans). Schuylkill River, Pennsylvania 
(Leidy, ’82, under name M. alba). Pond near Bangor, Me. (J. C. S., ’83). Exhibited in New York 
(Helm, ’94). Lake St. Clair; Mona Labe, Muskegon County, Mich., and Horsehead Lake, Mecosta 
County, Mich. (Jennings, ’94). Sandusky Bay, Lake Erie (Kellicott, ’96). Waters connected with 
the Illinois River at Havana, 111. (Hempel, ’98). 
M . semibullata Hudson. — Waters connected with Illinois River at Havana, 111. (Hempel, ’98). 
TROCHOSPHJERA Semper. 
8. T. solstitialis Thorpe. 
Swamp near United States fish-hatchery, South Bass Island, in August, 1898. 
The genus Troclwsphcera was instituted by Semper in 1872 (Zeitschr. f. wiss. Zool., Bd. 22, p.311) 
for the remarkable rotifer Troclwsphcera equator! alls Semper, found by that author in the Philippine 
Islands. Trochosphcera equatorialis, as is well known, is a spherical rotifer, with a girdle of cilia divid- 
ing the surface of the sphere into two hemispheres. It approaches closely, in many respects, to the 
structure of the Trochophora larva of annelids and mollusks, and great importance has been attached 
to it as the nearest representative of the hypothetical ancestor of those groups. Trocliosplutra seems 
not to have been seen again until found by Surgeon V. Gunson Thorpe, of the English Navy, in 1889, 
at Brisbane, Australia. In 1892 the same investigator discovered in China a second species of the same 
genus, differing from T. equatorialis in that the ciliary girdle passes not around the middle of the 
sphere, but nearer one pole, like the tropic of Cancer around the earth. To this species Thorpe (’93) 
gave the appropriate specific name solstitialis. Much interest was aroused when in 1896 (Science, 
Dec. 25, 1896) Ivofoid announced the discovery of T. solstitialis Thorpe in the Illinois River and waters 
connected therewith near Havana, 111. Kofoid raised the question whether its presence in America 
was due to recent importation from China, or whether it is to be considered a native American form. 
Its occurrence at a station so distant from that recorded by Kofoid, on a small island in Lake Erie, 
seems to indicate that the latter alternative is probably correct. It is not unlikely that Trocliospliasra 
will be found to be widely distributed in America when proper search for it is made. 
The swanrp in which Troclwsphcera occurred at Put-in Bay has over its bottom a dense growth of 
Ceratophyllum, while the surface is completely covered with a mantle of plant material consisting of 
Lenina, Spirodela, and Wolffia intermixed. It is connected with the lake by a narrow short channel, 
and is situated at such a level that when the lake is high it receives water from the lake, while under 
the usual conditions water flows out of the swamp into the lake. Many of the Rotifera in the swamp 
are common to it and to the lake, while a number were found in the swamp alone; among the latter 
was Trochosphcera. The animal was never abundant, only a few individuals being obtained, and it 
was found for only a few days in August. 
Waters connected with the Illinois River at Havana, 111. (Kofoid, ’96, and Hempel, ’98). 
CONOCHILUS Ehrenberg. 
9. C. unicornis Rousselet. 
Common in surface towings and plankton hauls from Lake Erie in the region of South Bass 
Island and from East Harbor. 
Lewis Lake and Yellowstone Lake in the Yellowstone Park (Forbes, ’93, under the name C. 
leptopus Forbes). Lake St. Clair (Jennings, ’94). Sandusky Bay, Lake Erie (Kellicott, ’97). Waters 
connected with the Illinois River at Havana, 111. (Hempel, ’98). 
C. volvox Ehrenberg.— Water from Plainfield, N. J. (Hitchcock, ’81 b). Bangor, Me. (J. C. S., ’83). 
Exhibited in New York (Balen, ’85, Helm, ’89, and Walker, ’94). Quincy Bay, Mississippi River, Illi- 
