21. 



0*028 ram. in length. The oesophagus und*?r Average extension 

 is about 0.14 ram. long while the bifurcation of the 

 intestine is about 0.25 *a:a. in length. 



The .-jiovezaent of the carcaria is aooo rap li shed in two ways, 

 one of which is much slower than the oth^r. The slower 

 laoveiaent is leech -li^e and is used only on a surface* Vhia 

 is the only ,oovora<mt possible undr the cover glass. When 

 free in the wat*?r, however, the movement is vigorous* The 

 body, which is concave Centrally between the suckers, is 

 doubled in to the ventral sudker. The posterior end also 

 is doubled in ac that the boity is almost in a ball. 15ie 

 tail then lasher vigorously baoV and forth, mostly in one 

 plan, irivintj the ceroaria at a hig)i rate of speed but 

 in no definite direction. The duration of this vigorous 

 5Qov^ra*mt i? usually le^e than twenty -four hours altho longer 

 periods of activity have occasionally b??en seen. Xhis 



veraent ia almost identical witli that described by Oort 

 ^r Qer<y*ri.a tri.tp.Ji^ia, Oort (1915, p 3V). 



Bxiretory System 



The excretory system of the oerearia of 33ohlnpB T U>inii 

 revo lutum (fig. 47) proved to be extremely difficult to 

 wcrX out. The difficulties were due principally to two 

 things. Pirst to the faot that the entire body from the 

 region of the pharynx to the posterior end is filled with 

 eystogenous glands whioh are somewhat opaque* The longer 

 the oeroaria^ are free in the water the more opaque these 

 glands become. '#ie second difficulty is due to the com- 

 plexity and progressive modification of the accessory 



