TREMATODES FROM FISHES — CLINTON 11 



There are about 38 small tubercular spines on each lateral margin, 

 beginning a short distance from the anterior suckers and extending to 

 the posterior sucker. They are short, tending to pyramidal in shape, 

 and are surmounted by three short tines. No eye spots were seen. 

 There is a membranous border to both anterior and posterior suckers. 



Suborder Polyopisthocotylea Odhner, 1912 



Family ONCHOCOTYLIDAE Monticelli, 1903 



Genus ONCHOCOTYLE Diesing, 1850 



ONCHOCOTYLE MAVORI, new species 

 Plate 15, Figures 189-196 



The specimens here described were given to me by Dr. James W. 

 Mavor, who had found them on tlie bottom of an aquarium in which 

 were a number of white perch {Morone americana), from Tashmoo 

 Pond, Marthas Vineyard, Mass. 



Since these trematodes were not found on the gills of the perch, and 

 since the genus Onchocotyle has been recorded only from the gills of 

 selachians, there is naturally some doubt as to the perch being their 

 host. 



The following description is based mainly on a study of whole 

 mounts in balsam : 



The body proper is somewhat lanceolate, tapering more anteriorly 

 than posteriorly. Anterior sucker nearly terminal, sharply marked 

 off from the body by a constriction. The posterior sucker-bearing 

 portion is approximately half the length of the body proper, and 

 usually nearly at right angles to it. At the anterior ventral half 

 of the sucker-bearing portion there are three pairs of relatively 

 large circular suckers, equal in size and sessile. Each of these suckers 

 is supported by a strong, sickle-shaped chitinous hook, the posterior 

 end of which is blunt while the anterior end terminates in a slender, 

 recurved claw. The hook agrees closely with Olsson's figure of the 

 corresponding hook in 0. emarginata.^ The posterior half of the 

 sucker-bearing portion tapers gently to a blunt, bifid termination, 

 consisting of two small terminal suckers, longer than broad, and open- 

 ing posteriorly. On the median line between the bases of these 

 terminal suckers there is a pair of small hooks, which appear narrow 

 in dorsoventral view but in lateral view are seen to have relatively 

 broad bases, from which they taper to sharp-pointed and recurved 

 ends. The genital pore is on the median line a short distance back 



^ Kongl. Svenska Vetensk. Akad. Handl., ser. 2, vol. 14, No. 1, pi. 2, fig. 26, 1876. 



