242 Zoology of Colorado 



perished from the liver-fluke, and no help seemed available, until 

 a student of worms discovered the life story of the parasite, and 

 how it abode in a common fresh water snaih 



FLAT-WORMS 



The free-living forms, known as Planarians, are found in 

 fresh water and on the land. No terrestrial species have been 

 found in Colorado, and presumably none exist, the climate being 

 too dry. A dark colored aquatic form, looking like a small flat 

 slug, is not rare in mountain springs, but it has not been identi- 

 fied.* A very minute animal, resembling some of the ciliate 

 Protozoa, has been observed at Boulder. It belongs to the 

 Order Rhabdocoelida, but its exact classification is unknown. 

 The parasitic flat-worms include the Trematodes or flukes, and 

 the Cestodes or tape-worms, both of considerable economic im- 

 portance. The fluke Fasciola magna of Bassi was found at Colo- 

 rado Springs, infesting the liver of cattle. Hassall in 1891 re- 

 garded the specimens as representing a new species (F. carnosa), 

 but this apparently was a mistake. Ward (1918) places the 

 species in a new genus, which he calls Fascioloides, distinguished 

 superficially by the broad form, with no snout-like anterior pro- 

 jection. This fluke was originally discovered in the wapiti (our 

 so-called elk) in a zoological garden in Europe. 



Cestodes or tape-worms are as frequent in Colorado as else- 

 where. Hall** gives a long list of records, the various species in- 

 festing mammals (including man), birds, and even amphibians 

 and fishes. Thus Davainea salmoni of Stiles was found to be 

 very common in the intestine of cottontail rabbits in Elbert and 

 El Paso Counties; it is a worm about 88 mm. long and three wide. 

 A different tape-worm, Cittotaenia mosaica of Hall, was described 

 in 1908 from a cottontail collected near Seven Lakes. It is 

 easily separated from the other by the fact that the scolex ("head") 

 is without hooks. Hall in 1912 reported that the gid parasite 

 infesting the brain of sheep had no foothold in Colorado, though 

 established in northern Montana. This animal, Coenurus multi- 

 ceps of Leske,*** lives as an adult worm in the dog, and it is the 



*In 1922 specimens of Planaria maculata and P. dorotocephala were liberated by Miss 

 Dorothy Young in the pond on the University of Colorado campus. 



**The Parasite Fauna of Colorado. Colorado College Publication. Science Series, Vol. 

 XII, No. 10 (1912). 



***Concerning the name, see Nature, March 9, 1922, p. 310. 



