ROTATORIA OF THE UNITED STATES. 
93 
in the latter. An animal fulfilling precisely these requirements is very abundant, and is shown in 
figs. 35 and 36, plate 20. This seems unquestionably the animal figured under the name M. cornuta by 
Hudson and Gosse; by Levander (’94); by Bryce (’91), and by Ehrenberg himself (’38). The animal 
figured as M. cornuta by Eckstein (’83) is too broad and deeply excised at the anterior margin for this 
species ; it seems more likely to have been M. lunaris Ehr. « 
For M. bulla, Gosse’s specific characters are as follows: “ Lorica a pointed oval; dorsal and 
ventral plates both gibbous and nearly coequal; toe rod-shaped in vertical aspect, with a two- 
sliouldered claw, but decurved and tapering gradually in lateral aspect.” Further along in his 
description he says that the true distinctive characters are “ The great rotundity of the ventral plate, 
the regular decurvation of the tapered toe, and the deep narrow sinus in both the occipital and the 
pectoral fronts of the lorica,” his figure 4c showing that the sinus in the front of the ventral plate of 
the lorica (“pectoral front”) is deeper than that in the dorsal plate. An animal fulfilling all these 
conditions and agreeing with Gosse’s figures is one of the most abundant rotifers in America. It is 
shown in figs. 37, 38, and 39, plate 21. This is the species figured by Eckstein (’83) and Weber (’98) as 
M. lunaris. As already pointed out, the contours of the anterior margins of the lorical plates abso- 
lutely forbid that identification, while they as clearly point to M. bulla Gosse as the correct determina- 
tion. The same animal is figured by Stokes (’966) as M. bipes n. sp. Stokes bases his new name on 
the fact that there is a line running lengthwise in the middle of the small claw (a fact that had been 
noted or figured by various previous observers), and that he has seen the two halves of the claw spread 
apart at this line in dead specimens. Stenroos (’98) finally figures this animal correctly, as I believe, 
as M. bulla Gosse. The animal figured by Weber (’98) as M. bulla seems, to judge from Weber’s 
figures, to have had almost none of the distinctive features of M. bulla Gosse. 
I give the distribution of these four species in the following four numbers: 
75. M. quadridentata Ehr. (Plate 21, fig. 40.) 
Very abundant in the bottom and littoral vegetation of shallow parts of Lake Erie about South 
Bass Island and in the swamps on the island. 
Minnesota (Herrick, ’85). Near Cincinnati, Ohio (Turner, ’92). Lake St. Clair and Crooked 
Lake, Newaygo County, Mich. (Jennings, ’94). West Twin Lake, Charlevoix, Mich. (Jennings, ’96). 
Sandusky Bay, Lake Erie (Kellicott, ’96). Trenton, N. J. (Stokes, ’96a). Waters connected with the 
Illinois River, at Havana, 111. (Hempel, ’98). Pond, Hanover, N. II. (II. S. J.). 
76. M. lunaris Ehrenberg. (Plate 21, fig. 41.) 
Synonym. — M. corn uta Eckstein (’83). (?) 
Common in littoral and bottom vegetation of Lake Erie about South Bass Island and in the 
swamps on the island. 
Shiawassee River at Corunna, Mich. (Kellicott, ’88). Near Cincinnati, Ohio (Turner, ’92). Lake 
St. Clair and the following inland lakes of Michigan: West, Twin Lake, Muskegon County; McLaren 
Lake, Oceana County ; Crooked Lake, Newaygo County ; Chippewa Lake, Mecosta County (Jennings, 
’94). Round Lake and Old Channel, Charlevoix, Mich. (Jennings, ’96). Sandusky Bay, Lake Erie 
(Kellicott, ’96). Waters connected with the Illinois River at Havana, 111. (Hempel, ’98). 
77. M. cornuta Ehrenberg. (Plate 20, figs. 35 and 36.) 
In littoral and bottom vegetation of Lake Erie about South Bass Island and in the swamps on 
the island. 
New York (Ehrenberg, ’43). Shiawassee River at Corunna, Mich. (Kellicott, ’88). Lake St. Clair; 
West Twin Lake, Muskegon County, Mich., and White Lake, Muskegon County, Mich. (Jennings, ’94). 
Pool on shore of Pine Lake, near Charlevoix, Mich. (Jennings, ’96). Waters connected with Illinois 
River at Havana, 111. (Hempel, ’98). Pond, Hanover, N. H.; Swamp near Norwich, Vt. (H. S. J.). 
78. M. bulla Gosse. (Plate 21, figs. 37, 38, and 39.) 
Synonyms — M. lunaris, Eckstein (’83), and Weber (’98). M. bipes Stokes (’966). 
One of the commonest rotifers among aquatic plants in parts of Lake Erie about South Bass 
Island and in the swamps on the island. 
Shiawassee River at Corunna, Mich. (Kellicott, ’88). Lake St. Clair and the following inland 
lakes of Michigan: McLaren Lake, Oceana County; Crooked Lake, Newaygo County; Chippewa 
Lake, Mecosta County (Jennings, ’94). Old Channel and West Twin Lake, near Charlevoix, Mich. 
(Jennings, ’96). Sandusky Bay, Lake Erie (Kellicott, ’96). Waters connected with the Illinois River 
at Havana, 111. (Hempel, ’98). 
