72 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.88 



Table 17. — Record of specimens of Podocotyle olssoui collected from tomcod 



Month 



Average 

 number 

 per host 



January.. 

 February. 



March 



April 



May 



June 



July 



August 



September 



October 



November. 

 December. 



3.06 

 10.56 

 2.85 

 4.45 

 1.20 

 11.42 

 1.25 

 .08 

 2.06 

 1.55 

 1.47 

 4.78 



Measurements of one in balsam: Length, 4.66 mm., breadth, 

 0.7 mm. ; oral sucker, length, 0.2 mm., breadth, 0.22 mm. ; pharynx, 

 length, 0.11 mm., breadth, 0.13 mm. ; ventral sucker, length, 0.34 mm., 

 breadth, 0.39 mm. ; length of esophagus, 0.08 mm. ; breadth of testis, 

 0.42 mm.; ova, 0.072 by 0.039 mm. Measurements in formalin: 

 Length, 6.15 mm., breadth, 0.65 mm.; diameter of oral sucker, 

 0.25 mm., of pharynx, 0.1 mm., of ventral sucker, 0.4 mm. ; ova, 0.084 

 by 0.056 mm. 



From the white perch: As in distomes from other hosts there is 

 here a considerable variation in size and in details of structure. The 

 smallest, in balsam, is 1 mm. in length and 0.11 mm. in diameter; the 

 largest, 4.9 mm. in length and 0.56 mm. in breadth. The esophagus 

 is as long as the pharynx. In many cases the vitellaria are not inter- 

 rupted at the level of the testes. In some the A^tellaria are inter- 

 rupted on one side and not on the other. Cirrus smooth with basal 

 bulb. Breadth of testis one-half or more the breadth of the body. 



One, collected August 8, 1906. Fifteen, collected July 20, 1910. 

 Collected by Vinal N. Edwards on six dates in four years, in April, 

 May, and October, one to six on each date ; 16 in all ; lengths 2 to 4 

 mm. in formalin. (U.S.N.M. No. 8237.) 



From the grubby : Collected from this host by Vinal N. Edwards 

 on three dates: Three, December 23, 1905; length, 5.5 mm. in for- 

 malin. Two, April 14, 1910; 10 fishes examined; length, 3.5 mm. in 

 formalin. Thirteen (U.S.N.M. No. 8238), February 3, 1915; 8 fishes 

 examined. The smallest specimens, about 2 mm. in length and 

 0.5 mm. in breadth, are immature. Others with ova from 2.8 to 4.13 

 mm. in length. Measurements in balsam : Length, 3.71 mm., breadth, 

 0.66 mm.; oral sucker, length, 0.18 mm., breadth, 0.22 mm.; pharynx, 

 length, 0.13 mm., breadth, 0.14 mm. ; ventral sucker, length, 0.18 mm., 

 breadth, 0.22 mm.; breadth of first testis, 0.35 mm,; ova, 0.075 by 

 0.045 mm. 



