TREMATODES FROM FISHES — LINTON 113 



From horse mackerel: Sixteen (U.S.N.M. No. 8310), collected 

 June 16, 1911. Note made on formalin material: Much variation in 

 size. Measurements, largest: Length of body, 17 mm., of neck, 5 

 mm.; diameter of body, 6.7 mm. Smallest, length of body 5 mm., 

 of neck, 2.5 mm.; diameter of body, 2.25 mm. In all of these dis- 

 tomes both the body and neck were cylindrical, or nearly so, and 

 the neck was reflected nearly, and in some cases, quite at right angles 

 to the body, in most cases arcuate, but in some straight. 



Four, collected June 23, 1911. Measurements in formalin: 

 Largest, length of body, li mm., of neck, 3 mm. ; diameter of body, 

 3 mm. 



Fourteen (U.S.N.M. No. 8310), collected August 8, 1913, from 

 stomach of host. Pale, translucent pink to brick red, with dark 

 brown intestines showing through the body wail; actively contract- 

 ing. Smallest, at rest, length about 15 mm., largest, 30 mm. When 

 placed in sea water they exhibited a tendency to adhere to each 

 other by their ventral suckers. 



Two, collected July 31, 1914, in stomach of host. 



One (U.S.N.M. No. 8308), collected June 29, 1915. This specimen 

 stretched to a length of 40 mm. in sea water, and contracted to 20 

 mm. when placed in killing fluid. Measurements of a specimen 

 from the horse mackerel mounted in balsam: Length, 14 mm.; 

 breadth, 3.25 mm. ; oral sucker, length, 0.92 mm., breadth, 1.00 mm. ; 

 breadth of pharynx, 0.56 mm.; ventral sucker, length, 1.82 mm., 

 breadth, 1.78 mm. The testes in this specimen, at the posterior edge 

 of the ventral sucker, are nearly transverse, their median ends touch- 

 ing each other; right testis, length, 0.42 mm., breadth, 0.84 mm.; 

 left testis, length, 0.56 mm., breadth, 0.84 mm.; each testis tapers 

 laterally from its median end. Ovary close to posterior edge of 

 testes, median, its anterior edge convex, posterior edge nearly 

 straight; length, 0.14 mm., breadth, 0.43 mm. The intestines are 

 voluminous, filled with dark-colored food material, and extend to 

 the posterior end of the body. In a series of cross sections (thick- 

 ness about 0.016 mm.) numbering about 776, the first trace of vitella- 

 ria is in the 237th section, and the last in the 538th. The voluminous 

 uterus, filled with enormous numbers of eggs, extends from a point 

 dorsal to the posterior edge of the ventral sucker, at about the 209th 

 section, to about the 510th section. Ova, about 0.036 by 0.024 mm. 

 The genital ducts associated with the shell gland agree closely with 

 the interpretation of sectioned material from the swordfish. In these 

 sections from the horse mackerel, however, the early folds of the 

 uterus contain sperm. The genital papilla, ejaculatory duct, pros- 

 tate, and metraterm in the distomes from the swordfish and horse 

 mackerel agree. In each the prostate is voluminous (figs. 138, 154). 



155599 — ^0 8 



