198 THE ROYAL SOCIETY OF CANADA 



Bass, which I sent to Dr. Ward, were considered by Cort (I.e., foot- 

 note p. 177) to belong to this species. 

 25. Allocreadium commune (Olsson). 16, pp. 499-503. 



Intestine of Catosiomus catostomus (Forster), Red Sucker, and 

 Fundulus diaphanus menona Jor. & Cop. ; and gall-bladder of Notropis 

 cornutus (Mitchill) , Red-fin or Shiner. 



The following are the respective measurements of the largest 

 specimens from the three hosts, in oil of cedar: Length, 0-89, 0-80, 

 1-05; breadth at acetabulum, 0-41, 0-42, 0-40; diameter of oral 

 sucker, 0-13, 0-17, 0- 13, of acetabulum, 0- 22, 0-22, -18; length of ven- 

 tral sucker, 0-19, 0-21, 0-20; pharynx, 0-085 X 0-068, 0-068 X 0-068, 

 0-060 X 0-051; eggs, 0-068 X 0-043,0-062 X 0-040,0-068 X 0-034. 

 These data compare favorably with those given by Odhner, excepting 

 in the case of the acetabulum, but the discrepancy may be accounted 

 for by the obvious fact that the specimens are all quite young. The 

 pharynx is more spherical than cylindrical, and there is no distinct 

 prepharynx. In many cases the anterior border of the subterminal 

 oral sucker slightly overhangs the aperture to form a sort of lip. In 

 all of the larger specimens the gonopore is situated in the m.edian line 

 just behind the forking of the oesophagus, being much closer to the 

 pharynx in contracted individuals, but in the small ones from the gall- 

 bladder of the Shiner it is situated slightly to the right or left of that 

 point, more often to the left. In these latter the seminal vesicle does 

 not reach to the posterior edge of the acetabulum, while in the former 

 it ends opposite the ovary. The ovary itself is placed on the right 

 side — in a few to the left — just anterior to the first testis, and is 

 smaller than either of the testes which are equal in size and situated 

 in the median line (Fig. 18). In much contracted examples the ovary 

 may lie to the right side of and dorsal to the acetabulum. The 

 vitellaria extend from the pharynx to the posterior end, greatly 

 obscuring the rest of the reproductive organs, the intestinal coeca and 

 even the acetabulum (when viewed from above). 



Very small distomes, 0-22 X 0-06mm., showing no traces of 

 reproductive organs as yet but otherwise resembling the smallest of 

 those from the Red-fin, were taken from the swim-bladder of a minnow, 

 Notropis atherinoides{?). 



On June 4, 1912, Mr. W. A. Clemens drew my attention to the 

 fact that a living may-fly nymph of the genus Blasturus (sp. ?) which 

 he had collected near the Station at Go-Home, harbored a living worm. 

 A closer examination showed that this worm, which could be clearly 

 seen through the transparent exoskeleton of the host, was moving 

 backwards and forwards to the left of the nymph's intestine and 

 consequently keeping in motion a large number of eggs and several 



