BY ELEAXOt; K. ('HASE. 



501 



The dingiug plug exfciuls a sbort distance I)eyoiul tlie margin of the beaker- 

 shaped anterior region, and the genital papilla also projects a short distance 

 from the bursa posteriorly. (Text-flg. 1.) 



f^eg. iiL. lit 



Text. fig. 1. — Holosliiiuiii ripiiis, ii.sp. 



In all the described species of Hnlostomum, the oral sucker and tlie pharynx 

 are both well-defined structures, but in H. repens only one cavity with thick mus- 

 cular walls is found in connection with the mouth. With the limited amount 

 of material at my disposal, a difBeulty has been experienced in determining 

 whether this structui'e represents an oral sucker, or pharynx, or a union of the 

 two. In the -Trematoda the absence of a pliai-ynx is not common, ;dtb(]ugh it 



