728 THE AMERICAN NATURALIST. [VoL. XXXV. 
by almost all later authors. Certain families, as the Apsilide, 
Ploesomadze, Gastropodidz, and Anapodidz, are added to those 
given by Hudson and Gosse; this has become necessary through 
the progress of investigation since the monograph was written. 
Many of the definitions are taken from Hudson and Gosse. 
The system is based throughout on the structure of the 
females. 
SYNOPSIS OF THE ROTATORIA, WITH CHARACTERS OF 
THE CLASS, SUBCLASSES, AND ORDERS. 
Crass RoTATORIA OR ROTIFERA (WHEEL ANIMALCULES). 
Small microscopic organisms, living chiefly in fresh water, bearing at the 
anterior end a ciliated area which takes various forms. Body often extended 
backward to form a stalk or foot. Pharynx with chitinous jaws ; cloacal 
opening, when present, on the dorsal side, at the boundary between body 
oot. Excretory organs in the form of fine tubes bearing “ flame cells " 
or “ vibratile tags,” and opening into a contractile vacuole near the cloaca. 
Sexes separate ; males usually minute, .degenerate, lacking the alimentary 
canal 
SuBCLASS 1, DicoNoNTA (HAVING Two OVARIES). 
Order 1. Bdelloida. Swimming with the ciliary wreath and creeping like 
a leech (or parasitic). Jaws ramate (Fig. 34). 
Family i. Philodinadz. 
Genera. Philodina, Rotifer, Callidina, Discopus. 
Family 2. Adinetade. 
Genus. Adineta. 
Order 2. Seisonacea. Marine ; parasitic on Nebalia ; no corona. Males 
Genera. Seison, Paraseison, Saccobdella. 
SUBCLASS 2, MONOGONONTA (HAVING ONLY ONE OVARY). 
Order 4. , Rhizota. Fixed forms ; foot ending in a disk or cup. 
Genera. Floscularia, Stephanoceros. 
Family 5. Apsilide. 
Genera. ae E (Atrochus). 
Family 6. Melice 
Genera. Me viii: Gadi Limnias, Limnioides, Cephalosiphon, 
CEcistes, Pseudcecistes, Lacinularia, Megalotrocha, Conochilus. 
