404 EOTIFERA. 



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 (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. Floscularia proltoscidea Ehrbg., 

 Steplianoceros Eiclilwrnii Ehrbg., Tubicolaria najas Ehrbg., Mcliccrta ring ens 

 L., Conochilus volvosc, Ehrbg. 



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

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

 without gelatinous investment. Callidina elcgans Ehrbg., Rot'ifer vulgaris 

 Oken (R. rcdivivus Cuv.), Pliilodina crytliroplitlialma Ehrbg. 



Fam. Brachionidae. Rotifera with bifid or multifid wheel-organ ; with 

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

 Brachionus Balteri 0. Fr. Mull., B. militaris Ehrbg., Euchlanis triqiietra 

 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 setge or pincer -shaped. Ilydatina Ehrbg., II. scuta 0. Fr. 

 Mil", with Entcroplea liydatince Ehrbg., as male. Notommata tardigrada 

 Ldg., N. Brackionus Ehrbg., N. parasita Ehrbg. 



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

 and anus. Asplanclina Sieboldii Ldg., A. myrmeleo Ehrbg., Ascomorplia 

 germanica Ldg. 



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

 Echinoderidse which Dujardin and Greef regarded as connecting links between 

 Vermes and Artliropoda (Echinodercs Dvjardinii Clap., E. setigcra Greef) ; 

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



* Compare E. MeUclmiTtoff, " Ueber einige wenig bekannte niedere Thier- 

 formen," Zcitschr. fur miss. Zool., Tom. XV., 1865. Also the works of 

 H. Ludwig and 0. Butschli. 



