STUDIES ON' THE ECTOPARASITIC TREMATODES OP JAPAN. 257 



arrangecl iu a liorse-slioe shape ; penis with 



10 hooks D. tetrodonis. p. 213. 



i* Body always symmetrical ; with a pair of exceedingly 

 small spheroidal suckers within the mouth, and with 

 four pairs of semi-ellipsoidal suckers at the posterior 

 end of the body, the innermost pair of which is 

 considerably smaller than the others ; with two pairs 

 of hooks between the innermost pair of posterior 



suckers HEXACOTYLE. p. 217. 



*'Body acutely pointed iu front, broad in the 



middle portion as well as at the posterior end, 



about 11 mm. long; with the outer pair of 



hooks at the posterior end solid, about 0.09 



mm. long ; vagina armed with chitinous teeth.H. acuta, p. 217. 

 *2 Body with a lateral swelling on each side close 



to the front end, with the anterior portion 



slender, broad in the middle part as well as at 



the posterior end, about 18 mm. long; with the 



outer pair of hooks hollow and about 0.125 mm. 



long; vagina armed with chitinous teeth ...H. grossa. p. 220. 

 f^Body always , symmetrical, elongated and slender; 

 with an ellipsoidal sucker around the mouth-cavity ; 

 with three pairs of hemispherical suckers at the 

 posterior end of the body, each with a semicircular 

 chitinous rod with a claw at one end ; with a sub- 

 cylindrical appendage projecting from between the 



foremost pair of suckers ONCHOCOTYLE. p. 223. 



"'*' Posterior suckers arranged in a horse-shoe 



shape ; appendage bifid at the extremity, with 



a pair of small suckers at the bifid end, and a 



pair of hooks between them ... 0. spinacis. p. 224. 



i^ Body always symmetrical, flat, heart-shaped ; with 

 a rudimentary sucker around the mouth ; with 

 a circular posterior sucker, the internal surface of 

 which is divided into a subcentral and seven peri- 



