ROTIFERA 



237 



2. AsPLANCHNOPUS De Gueriie. Foot present; animals viviparous: 

 2 species. 



A. multiceps Schrank. Foot small; length 1 mm.: pelagic. 



Family 3. TEIARTHRIDAE. 



Foot absent; long paired appendages at the side by means of which 

 the animal skips or swims and which may give it the appearance of a 

 crustacean: several genera. 



PoLYARTHRA Ehrenberg. Body rectangular with 12 long blade- 

 shaped appendages with serrate edges arranged in 

 4 groups: 1 species. f^^JJIIl!!^^ — 1 



P. platyptera Ehr. (Fig. 378). One eye pres- 

 ent; length .15 mm.: very common both at surface W P ^\\n S 

 and bottom. 



Family 4. HYDATINIDAE. 



Body cylindrical or sac-shaped with a short 

 foot which has 2 small toes ; corona with a number 

 of elevations bearing setae: 5 genera. 



1. Hydatina Ehrenberg. With- 

 out eyes, but with a tentacle: 8 

 species. 



H. senta* Ehr. (Fig. 379). 

 Body large, .5 mm. long, trans- 

 parent: often common. 



2. NoTOPS Hudson. Single eye 

 present; corona large with a ring 

 of cilia and bearing several large 

 prominences crowned with setae: 

 several species. 



N. brachionus (Ehrenberg) 

 (Fig. 380). Body large, quadran- 

 gular and transparent; foot half as long as body 

 length .5 mm. : often common. 



Fig. 380 



Notops 



brachionus 



(from Siissw. 



F. Deut.). 



Fig. 379 



• Hydatina senta 



(Siissw. F. Deut.). 



1, corona ; 2, mouth ; 



3, mastax ; 4, gastric 



gland ; 5, stomach ; 6, 



. ovary ; 7, yolk gland ; 



8, lateral sense organ ; 



9, intestine ; 10, kid- 

 ney tubule ; 11, vacu- 

 ole: 12, anus; 13, 

 adhesion glands ; 14, 

 toes. 



and little retractile; 



Family 5. NOTOMMATIDAE. 



Body soft and elongate; corona oblique in position, without lobes, 

 and covered with cilia and often with a pair of lateral ciliated projec- 

 tions called auricles: 15 genera, 



* See "Studies in the Life Cycle of Hydatina senta," by A. P, Shall, Jour. Ex. 

 Zool., Vols. 8, 10, and 12, 1910-1912. "The Influence of FoQd in Controlling Sex in 

 Hydatina senta," by D. D. Whitney, same. Vol. 17, 1914. 



