r6tIFERS. 221 



which it encloses. The Key refers only to those 

 forms included in this book. 



Key to Some Genera of Rotifera. 



1. In an attached, gelatinous or o±her kind of sheath 



2. Not in a sheath, but in attached clusters {d). 



3. Free-swimming singly or in a clustered group (e). 

 a. Clustered; sheaths soft, gelatinous, colorless; 



ciliary disk single, heart-shaped, Lacinuldria, i. 

 a. Not clustered, but sometimes in family groups; 

 sheath gelatinous (S). 



a. Not clustertd; sheath not gelatinous (c). 



b. With five long, erect, ciliated arms on the front 



border, Stephanoceros, 2. 

 b. With several (from 2 to 7) groups of many long, 

 fine, radiating hairs (set») on 'the front border. 

 Flosculdria, 3. 



b. With a broadly oval or circular ciHary disk; 



sheath gelatinous, semi-opaque, or with pellets, 

 CEcistes, 4. 

 £. Sheath formed of rounded, brownish pellets, 

 MeltcMa, 5. 



c. Sheath not formed of pellets, but membranous; 



brownish or colorless, Limnias, 6. 



d. Ciliary disk horseshoe-shaped, Megaldtrocha, 7. 



e. In a cluster of coherent, gelatinous tubes; ciliary 



disk horseshoe-shaped, ConochUus, 8. 

 e. Not clustered; with lorica {g). 

 e. Not clustered;- without lorica; ciliary disks two 



(/)• 

 /. Eyes two, cervical, Philodina, 9. 



