378 



BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



of body for a distance of 1.1 mm. from head end. Esophagus 9.6 

 mm. long. Vulva 175/z from posterior end (fig. 438e). Eggs 75 

 to 79jm long by 40 to 44/x wide; shells not pitted, as in other species, 

 but with an irregular network of ridges (fig. 438/). 



Life history.— Unknown ; see H. tricolor, p. 376. 



Distribution. — South America (Brazil). 



HYSTRICHIS CORONATUS Molin, 1861 



Synonyms. — Hystrichis, species Molin, 1860; H. mergi-mergan- 

 sei^is Diesing, 1861. 



Host. — Primary: Mergus merganser; secondary: Unknown, prob- 

 ably fish, according to Jaegerskiold. 



Location. — Glands of proventriculus. 



Fig. 438. — Hystrichis acanthocephalicus. a, Side view ; b, front view of 



HEAD; C AND d, MALE TAIL; e, FEMALE TAIL; f, EGG. AFTER JAEGERSKIOLD, 



1909 



Morphology. — Hystrichis (p. 375) : Head (fig. 439a) not set off 

 from body. Only one circle of spines; it is directly posterior to 

 mouth and, according to figure, made up of 18 large spines. Pos- 

 terior region of body with coarse cross-striations or annulations. 



Male unknown. 



Female 27 mm. long ; maximum width 3 mm. According to figure 

 (fig. 4396), body considerably swollen in middle region. Vulva near 

 to anus, at the rounded posterior end of body (fig. 439c). 



Life history. — Unknown; see H. tricolor, p. 376. 



Distribution. — Europe (Italy (Padua)). 



HYSTRICHIS CYGNI (Molin, 1858) Diesing. 1861 



Synonyms. — Echinocephalus cygni Molin, 1858 ; Hystrichis pachi- 

 cephalus Molin, 1861a. 



