368 



BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



(life history) and see also E. ignotus, p. 371), according to Jaeger- 

 skiold and to Ciurea. 



(Location. — Intestine. 



Morphology. — Eustrongylides (p. 367) : The middle of the worm 

 is much thickened, the extremities are slenderer, the anterior por- 

 tion longer and slenderer than the posterior. The 6 papillae near 

 the mouth (fig. 4276) very small and those outside of these are 

 larger but inconspicuous. Cuticle grossly annulated, the annulation 

 almost disappearing in the middle portion of the body. The mouth 

 aperture is usually triangular, but may be 6-angled and give the 

 impression of being round. The mouth cavity is triangular in cross- 

 section and is 100 to 160/x, long. 



Male 34 mm. long by 2 mm. wide. Bursal cup (fig. 427«) trumpet- 

 shaped, its margin with 2 incisions on the ventral surface. 



Fig. 427. — Eustrongylides tubifek. a, Male tail; 5, heiad 

 end; c, female tail. Aftek Jaegerskiold, 1909 



Female 35 to 44 mm. long by 2.5 to 3 mm. wide. Vulva near 

 anus (fig. 427 c). Vagina 11 mm. long. Eggs 65 to 75/x. long by 44ju 

 wide, oval with blunt ends and thick shells, the latter pitted. 



Life history. — Unknown; probably involves intermediate stages 

 in fish, according to Jaegerskiold and to Ciurea (1924). Larvae 

 described as Filaria cystica by Rudolphi from under the peritoneum 

 and in the muscle of certain fish (Symbranchus laticaudatus and 

 Galaxias scriba) were regarded by Jaegerskiold as the larva of a 

 species of Eustrongylides; see E. ignotu-s, p. 371. Recently Ciurea 

 has found similar larvae in certain fish (Ba.rhus fluviatilis, Lota 

 lota, Esox lucius, and Perca fluviatilis) in the Danube and regards 

 them as larval forms of some species of this genus. As E. tubifex 

 is the type species of the genus, Ciurea's larvae are figured here 

 (fig. 428 a to d) to show the probable nature of the larval Eus- 

 trongylides, the specific identity of the larvae not being ascer- 



