Acanthocephala 8i 



immature, though gravid females of this parasite have been taken 

 from the eel at Woods Hole, Mass., (Van Cleave, '13, p. 188), thus 

 indicating that the eel is not an accidental host but serves as a normal 

 definitive host in w^hich N. cylindratus may complete its develop- 

 mental cycle. 



The large-mouthed black bass (Micropterus salmoides) is the host 

 from which the type material of this species was taken in Pelican 

 Lake, Minn., (Van Cleave, '13, p. 187), yet the single specimen of 

 this species found infested in the Oneida Lake investigations car- 

 ried an extremly light infestation by this parasite. Thus it becomes 

 evident that a parasite may in different parts of its geographical 

 range infest the same host species in widely varying degrees. Not 

 only is there no necessary correlation between the distribution of a 

 parasite and that of its type host, but even when the range of the two 

 are coextensive the parasite may be the dominant parasitic guest of 

 entirely different hosts in different localities. 



Nothing is known regarding the development oi N. cylindratus. 

 Villot ('84) worked upon the development of a European representa- 

 tive {N. rutili) of the same genus, and found that the larval develop- 

 ment occurs in the aquatic larvae of Sialis. It is entirely probable 

 that some aquatic insect larva shelters the developing young of 

 ' N. cylindratus. 



P omphorhynchus bulbocoUi Linkins, 1919. 



Body elongate, tapering toward posterior end. Neck prominent, 

 measuring 2.6 to 4 mm. in length; diameter 0.15 to 0.4 mm. in pos- 

 terior region and 0.8 to 1.5 mm. in region of spherical enlargement. 

 Proboscis cylindrical, 0.5 to 0.6 mm. long by 0.7 to 0.2 mm. in dia- 

 meter, armed with 24 to 28 circular rows of hooks. Basal circle 

 with 12 hooks, remaining circles with 6 each. Embryos within body 

 cavity of gravid female 53 to 83/x long by 8 to i^/j- broad. 



In so far as known, fishes are the only normal hosts of the adult 

 parasite belonging to the genus P omphorhynchus. Many hosts 

 throughout the United States have been found to harbor this species 

 though there have been few published records of its occurrence, owing 

 to the fact that many of the early workers recorded the finding of 

 the European species in this country, without giving descriptions 

 sufficient to verify or disprove their claims. It seems probable that 

 all of the early records of Echinorhynchus proteus (= P. laevis) 

 from North America should be referred to the distinctively Ameri- 

 can species P. bulbocoUi. Only three species of fishes from Oneida 

 Lake were found to harbor P. bulbocoUi, but in addition a very 

 unusual instance of its occurrence in the water snake {Matrix 

 sipedon) was discovered. One specimen of A'', sipedon contained 

 five small individuals of this species in the stomach. The presence 

 in this host was, without doubt, accidental, the worms having been 

 taken into the stomach of the snake incidentally with one of their 



