260 



Planaria agilis n. sp. Fig. 2, 3, 4. 

 This planarian occurs frequently in small ponds near Lincoln. It 

 is also found at Omaha in large numbers in the many springs and small 

 spring-fed pools at the hase of the bluffs along the Missouri River. A 

 few specimens were collected by Dr. R. H. Wolcott from a spring-fed 

 brook in Monroe Canyon, Sioux County. It is found among algae, on 

 the under surface of sticks, dead leaves and stones, and glides about on 

 the sandy bottom of springs and pools, often where the water flows with 



Fiff. 2. 



Fiff. 3. 



Fig. 2. Planaria agiiis n. sp. From life. 



Fig. 3. Planaria agilis. Dorsal view of atrial organs. 



?«, Uterus; v.d, Yas deferens; s.v, Seminal vesicle; l.a, Limit of atrium; a, Atrium; 



p.l, Penis lumen; u.t, Uterus tube; o Oviduct; g p, Grenital pore. 



extreme swiftness. I have never found it in the larger lakes or the rivers, 

 of the state from which P. maculata has been obtained. 



Size of mature specimens collected at Omaha in November. 22 to 

 23 mm long, nearly 3 mm broad. Mature specimens collected May 29 in 

 Sioux County must have measured 30 mm when alive. Well fed spe- 

 cimens from aquaria of the University of Nebraska have measured 35 mm. 

 Average length of immature planaria 8 to IS mm. 



