404 EOTIFERA. 



without or with an inconsiderable and sometimes retrogressive 

 metamorphosis. This latter is most striking in the FlosvulcvridcR, 

 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, Algas, 

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

 others (Conochilus) 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. 



Fam. Floscularidae. Fixed Rotifera 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. Floscidaria proboxcide a Ehrbg.. 

 Stephanoceros Eiclihornii Ehrbg., Tubicolaria najas Ehrbg., Mdlccrta ring ens 

 L., Conochilus rolvox, Ehrbg. 



Fam. Philodinidae. Free, often creeping (in a looping manner) Rotifera ; 

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

 without gelatinous investment. Callidina elcgans Ehrbg., Rotifer xulgaris 

 Oken {R. redii-'mis Cuv.), Pltilodina crytliropldhalma Ehrbg. 



Fam. BracMonidse. Hot 'if era with bifid or multifkl wheel-organ ; with 

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

 Brachwnus Balteri 0. Fr. Mull., JB. militar/s Ehrbg., Eitchlanis triquetra 

 Ehrbg. 



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

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

 forked, with two seta; or pincer-shaped. Ifydatina Ehrbg., //. scnta 0. Fr. 

 Miul. with Entcroplea liydatinte Ehrbg., as male. Notommata tardiyrada 

 Ldg., N. Brachionits Ehrbg., N. parasita Ehrbg. 



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

 and anus. AsplaneJina Sicboldli Ldg., A. myrmeleo Ehrbg., AsconwrpJm 

 gvrmanica Ldg. 



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

 Echinoderidse which Dujardin and Greef regarded as connecting links between 

 Verities and Arthropoda (Ecliinodrrcs Dvjardinii Clap., E. sctigera Grcef) ; 

 and (2) the Gastrotricha * or Ichthydina (Cheetonotus). 



* Compare E. MetschniTtoff, " Ueber einige wenig bekannte niedere Thicr- 

 formen," Zuitschr. fur n-iss. Zool., Tom. XV., 1865. Also the works of 

 H. Ludwig and 0. Biitschli. 



