46 PROCEEDINGS OF THE NATIONAL MUSEUM vol.81 



Y shaped, situated ventral to ovary and testes. The limbs of the 

 vesicle extend anteriorly and unite at the level of the intestinal bi- 

 furcation at which point two branches are given off, one on each side, 

 which extend posteriorly in the lateral fields, then turn and i^ass 

 anteriorly to the level of the oral sucker, where they again turn and 

 pass backward and terminate near the posterior end of the body. 

 Long branches are given off here and there along the course of the 

 excretory ducts. Genital aperture median, situated a short distance 

 caudad of the oral sucker; the male and female genital pores are 

 situated side by side at the base of a short genital sinus. Cirrus 

 pouch cylindrical, 3 mm long by 300ju, wide, containing a seminal 

 vesicle, 1.4 mm long by 200/a wide, and a long convoluted ejaculatory 

 duct. The ejaculatory duct is lined with a membrane, which is 

 closely beset with small papillalike projections ; it may be protruded 

 as a slender cirrus the length of which may equal the length of the 

 body, according to Creplin (1829). Testes deeply lobed, 1 mm 

 long by 1.1 mm wide, situated in the same transverse plane in the 

 posterior fourth of the body ; vasa efferentia short, uniting to form a 

 relatively wide vas deferens which extends anteriorly in the median 

 line to the base of the cirrus pouch ; it then passes to the right of the 

 cirrus pouch where it makes several loops, four to five according 

 to Jiigerskiold, and then passes backward and enters the base of the 

 cirrus pouch. Ovary deeply lobed, 500/a long by 1 mm wide, situated 

 between the testes ; Mehlis's gland preovarial ; Laurer's canal present, 

 Vitellaria lateral, composed of 12 to 16 isolated follicles on each side, 

 lying ventral to ceca, and extending from the anterior margin of the 

 testes to about the level of the base of the cirrus pouch. Uterus 

 slender and greatly convoluted, extending laterally beyond the ceca 

 and from the testes anteriorly to about one-fourth of the body 

 length from the anterior end. Vagina muscular and lined with 

 spines which are about 35/x long. Eggs elongate oval in shape, 25/* 

 long, and provided with a long filament at each pole. 



Hosts. — Cetacea {Balacnoptera horealls^ B. musculus = B. physa- 

 libs, B. acutorostrata = Balaeiia rostrata) ; Pinnipedia - {Leptonycho- 

 tes weddellii., Lohodon carcinophaga) . 



Location. — Intestine. 



Distribution. — Europe (Norway) ; Antarctic waters (vicinity of 

 Cape Evans). 



Remarks.- — The above description is taken largely from an exhaus- 

 tive description of this species given by Jiigerskiold (1891). 



2 Johnston (1031) regards the form from pinnipeds as a species distinct from Ojmogas- 

 ter plicatus. The new species, for which he proposes the name 0. antarcticus, differs 

 from O. plicatus in " its smaller size, diflferent body proportions, presence of only 13 

 rugae, more restricted vitelline zone, and relatively smaller cirrus sac." 



