404 ROTIFERA. 



without or with an inconsiderable and sometimes retrogressive 

 metamorphosis. This latter is most striking in the Floscularidce, 

 which are fixed in the adult state. 



The Rotifera principally inhabit fresh water, in which they swim 

 about by means of the trochal disc, and sometimes they attach them- 

 selves to foreign objects by means of the forked glandular foot. 

 When thus attached, they extend the anterior part of the body, 

 and the cilia begin to move. The currents set up by the latter 

 convey to the mouth food material, such as small Infusoria, Algse, 

 Diatoms. Some species live in gelatinous sheaths and delicate tubes, 

 others (Gonochilus) are fixed by their foot in a common gelatinous 

 mass, and are united to form a free-swimming colony. A relatively 

 small number are parasitic. It seems that many species are able to 

 endure drying, if it be not too prolonged. 



Fain. Floscularidse. Fixed Rut/fern with a long transversely ringed foot, 

 usually surrounded by gelatinous coverings and tubes. The margin of the 

 head has a lobed or deeply cleft wheel-organ. Floscularia proboxcidea Ehrbg., 

 SteplianocefOS Eirliluirnii Ehrbg.. Tulii/'ular/a nnjax Ehrbg.. Milicrrta rinijens 

 L.. Conodiilus rolrox, Ehrbg. 



Fam. Philodinidae. Free, often creeping (in a looping manner) Rot if em ; 

 with double-wheeled rotatory organ, and jointed, telescopically retractile foot, 

 without gelatinous investment. CalUd'nta i-li-ijnns Ehrbg.. Sot if IT rulf/itris 

 Oken (7?. rcdivivux Cuv.), Pliilodina erytlirophthalma Ehrbg. 



Fam. Brachionidae. Rot'tfem with bifid or multifid wheel-organ ; with 

 broad, shield-shaped armoured body ; and foot ringed, or with short segments. 

 BracMonus Baltcri O. Fr. Miill.. ]>. iiiilifni-ix Ehrbg.. Euchlnnix triqurtra 

 Ehrbg. 



Fam. Hydatinidse. Edge of wheel-organ prolonged into numerous processes 

 (multifid) or only sinuous ; skin delicate, often ringed ; foot short, usually 

 forked, with two setas or pincer -shaped. Hydathia Ehrbg.. //. xenta 0. Fr. 

 Miill. with E>t1-('i-/n/li'n lii/flittinrr Ehrbg., as male, yotommatn tardlijrada, 

 Ldg.. N. Brachioniis Ehrbg., JV.jMrfixUti Ehrbg. 



Fam. Asplanchnidae. The sac-like unarmoured body is destitute of rectum 

 and anus. Aspla/ncJina S/cl/uliHi Ldg.. -1. mi/niit'li'o Ehrbg., Axromorjrfia 

 germanica Ldg. 



Two groups of small animals are allied to the Rotifera : (1) the 

 Echinoderidae which Dujardin and Greef regarded as connecting links between 

 Vrnii/'s and Arthropoda (EcJvinoderes I)ii/r<linii Clap., E. xctiycra Greef) ; 

 and (2) the Gastrotricha * or Ichthydina ( 



* Compare E. jUi'tscJiniknff', " Ueber einige wenig bekannte niedere Thier- 

 formen." Zi-itxclir. far w/xx. Zool., Tom. XV., LS6.~>. Al?o the works of 

 H. Ludwitr and 0. Biitschli. 



