142 . THE ROTATORIA. $ 181, 
Famity: Monorrocwa. 
Genera: Ptygura, Ichthydium, Chaetonotus, Ocecistes, Conochilus. 
Famity: Scurzorroca. 
Genera: Megalotrocha, Tubicolaria, Stephanoceros, Lacinularia, Melicerta, 
Floscularia. 
Famity: Potytrocpa. 
Genera: Enteroplea, Pleurotrocha, Hydatina, Notommata, Synchaeta, 
Polyarthra, Diglena, Triarthra, Eosphora, Cycloglena, Theorus, Masti- 
gocerca, Euchlanis, Salpina, Stephanops, Squamella. 
Famity: Zyeorrocwa, 
Genera: Rotifer, Actinurus, Philodina, Noteus, Anuraea, Brachionus. 
BIBLIOGRAPHY. 
See the works already cited under Infusoria. 
ADDITIONAL BIBLIOGRAPHY. 
Besides the writings of Brightwell, Hualey, Leydig, and others, quoted 
in my notes, see the following: 
O. Schmidt. Versuch einer Darstellung der Organisation der Rader- 
thiere, in' Wiegmann’s Arch. 1846. 
Frey. Ueber die Bedeckungen der wirbellosen Thiere. Gottingen, 
1851. 
See also the new edition of Pritchard’s Infusoria, given under Book. 
first. — Ep. 
CHAPTER I. 
CUTANEOUS SYSTEM. 
§ 181. 
Nearly all the Rotatoria are covered with a smooth,hard skin,® which 
is thrown into folds by the contractions of the subcutaneous parenchyma ; 
at the anterior extremity only, it is very delicate, and covered with vibra- 
tile organs, which also move to and fro with the parenchyma. With many, 
1 With Chaetonotus, and Philodina aculeata, spines. With Noteus, and Anuraea, there are 
the structure of the skin is quite different from species whose faceted skin is roughened by innumer- 
this ; for its surface bristles with stiff points and able granulations. 
