730 THE AMERICAN NATURALIST. [Vor. XXXV. 
Order 6. Scirtopoda. Swimming by means of branched appendages 
resembling in some respects those of the Crustacea. (The ordi- 
nal value of this character is decidedly doubtful.) 
Family 25. Pedalionade. 
Genera. Pedalion, Hexarthra. 
Of uncertain ‘sytematic position — Trochosphera, Atrochus, Adactyla, 
Balatro, Cypridicola. 
ARTIFICIAL KEY FOR THE DETERMINATION OF THE 
GENUS AND SPECIES OF AMERICAN ROTATORIA. 
Ar. Adult animals attached or united in colonies, usually dwelling in 
tubes; or if separate and free-swimming, then carrying the transparent 
tube with them. Foot ending in a flat disk or cup, which is attached 
to the substratum or to the bottom of the tube (or foot absent in 
Nos. 15-17) (free-swimming when young) Order RHIZOTA, H. & G. 
Br. Not forming colonies ; corona with long slender setze and usually 
produced into a varying number of lobes bearing the sete ; mouth in 
the center of the large corona ; cilia few, about the mouth, scarcely 
noticeable. Trophi uncinate (Fig. 10) . . Family FLOSCULARIAD/E 
ar. Sete not arranged in whorls or parallel rows on the lobes of the 
corona, but scattered or in groups . . . . Floscularia 
br. Free-swimming, carrying the trakopii tbe 
cz. Corona two-lobed ; two eyes on the dorsal lobe. 1, Floscularia 
mutabilis Bolton 
c2. Corona circular, ciliated, with five short prominences bearing 
sete . P3: 2, F. pelagica Rousselet (Fig. 1) 
ó2. Not ires eiim 
cz. Corona without distinct lobes, but pratend va set 
short, chiefly on the dorsal and ventral parts of the 
3, F. edentata pni (Fig. 2) 
æ 
c2. Lobes of the corona three 
dr. Lobes large, separated by iid curved depressions ; set On 
the entire rim of the corona. . 4, F. trilobata Collins 
(Fig. 3) 
d2. Lobes HOCUNE but three — one large dorsal and two small 
ventral ones ; but really with two minute additional lobes between 
the dorsal and ventral. See cj. 
£3. Lobes five 
dr. A long flexible process on the back of the dorsal lobe ; lobes 
knobbed  . 5, F. cornuta Dobie (Fig. 4) 
42. No dorsal process ; lobes kaobbed 
er. Lobes rather long and slender. . . . 6,4. onetta 
Cubitt (Fig. 5) 
e2 Lobes shorter and thicker . . 7, F. ornata Ehr. (Fig. 6) 
