114 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



The genital pore, as shown in sections, is on a level with the 

 pharynx. In a series of cross sections of a distome in which the 

 genital papilla is retracted, the genital pore is ventral to the pos- 

 terior end of the oral sucker. It is small and occupies only three 

 sections (thickness of sections about 0.016 mm.). The genital atrium 

 is represented by a duct, vertical diameter 0.11 mm., transverse 

 diameter, 0.22 mm., which continues in 47 sections, when it expands 

 at the genital papilla. At the thirteenth section back of the first 

 appearance of the genital papilla, the metraterm, with its thick, 

 muscular wall first appears. 



From goggler: One, immature (U.S.N.M. No. 8309), collected 

 August 17, 1913, from cyst on intestine. This distome, when re- 

 moved from the cyst, was subspherical, translucent, with a faint 

 tinge of pink ; intestines dark brown. 



Measurements in balsam: Length, 3.4 mm.; maximum breadth, 

 2.24 mm. ; oral sucker, length, 0.46 mm., breadth, 0.49 mm. ; diameter 

 of pharynx, 0.28 mm. ; ventral sucker, length, 0.74 mm., breadth, 0.88 

 mm. The body is strongly contracted, and the voluminous intestines, 

 containing dark brown granular material, conceal whatever rudi- 

 ments of genitalia may be present. 



From cutlassfish: One, collected July 1, 1903, from stomach of 

 host. Note on alcoholic specimen: Neck short, arched; body plump, 

 crossed by fine wrinkles ; length, 17 mm. ; breadth, 8 mm. ; thickness, 

 6.5 mm. ; breadth of neck at base, 4 mm., at level of oral sucker, 2.5 

 mm. Mr. Edwards reported that the worm when living was elon- 

 gated but contracted when placed in alcohol. 



The anatomy, as revealed by a series of cross sections, agrees closely 

 with Manter's description and figures of H. fusca. Details of the 

 genital ducts in the vicinity of the shell gland, as interpreted from 

 sections, are shown in figiire 150. The ova are not of uniform size, 

 and are somewhat smaller than those in the distome from the sword- 

 fish and horse mackerel. The largest noted measured 0.036 by 0.027 

 mm.; average dimensions of eight of the larger ova were 0.028 by 

 0.021 mm. 



The prostatic portion of the ejaculatory duct is nearly straight, 

 thus differing from the distomes of the swordfish and horse mackerel 

 in which it is more or less coiled. The ejaculatory duct, surrounded 

 by prostatic cells, enters the muscular genital papilla near the dorsal 

 side of the neck, extends back for a short distance, about 35 sections 

 of the series, along the dorsal region, then, at about section 130, turns 

 abruptly ventrad to the seminal vesicle at about the middle of the 

 length of the ventral sucker. The seminal vesicle, sections 115-158 

 of the series, is tubular and loosely coiled, as many as six divisions 

 of it appearing in a single section. The first (left) testis begins 

 dorsal to the posterior edge of the ventral sucker, and occupies sec- 



