NEMATODE PARASITES OF BIRDS 367 



Genus EUSTRONGYLIDES Jagerskibld, 1909 



Generic diagnosis. — Dioctophymidae (p. 366) : Body equally thick 

 throughout or thickened in median part. Head not enlarged, pro- 

 vided with 12 to 18 papillae, arranged as 2 circles. Cuticle of an- 

 terior and posterior extremities transversely striated, without spines. 

 Male with closed bell-shaped caudal bursal cup, the structure of 

 which is very typical for the individual species. One spicule, very 

 long. Female with anus in middle of rounded extremity; vulva 

 directly adjacent to anus. 



Parasitic in glands of proventriculus or other parts of digestive 

 tract of birds (for the most part aquatic birds feeding on fish). 



Type-species. — Eustrongylides tubifex (Nitzsch, 1819) Jaegers- 

 kiold, 1909. 



KEY TO SPECIES OF EUSTRONGYLIDES 



1. Unrecognizable species Eustrongylides papillosus, p. 373. 



Recognizable species 2. 



2. The inner crown of round, relatively low or very low papillae, more dif- 



ficult to see than the outer ; body proportionately short and thick, the 



female especially with much thickened middle region 3. 



Inner crown of papillae as high or higher than those of outer crown, easily 

 seen ; body slender, no thickening of middle region even in female 4. 



3. Papillae of outer circle relatively short, not digitiform. Mouth cavity com- 



paratively short, scarcely half as long as the width of the body at that 



level Eustrongylides tubifex, p. 367. 



Papillae of outer circle long (36 to 44/*), digitiform. Mouth cavity compara- 

 tively long, its length almost as great as the width of body at that level. 



Eustrongylides mergorum, p. 372. 



4. Six papillae in inner circle, 12 in outer, making a total of 18. 



Eustrongylides perpapillatus, p. 374. 

 Six papillae in each circle, making a total of 12 5. 



5. Papillae of both circles of same size and with narrow bases; mouth cavity 



very short, its length only % to % as great as body width at that level. 



Eustrongylides africanus, p. 369. 



Papillae of the outer circle of different size than those of the inner ; none 



of the papillae with narrow bases. Mouth cavity long, its length at 



least % as great as body width at that level 6. 



6. Margin of bursal cup entire, without incision. Eustrongylides ignotus, p. 371. 

 Margin of bursal cup with a deep incision on the ventral side. 



Eustrongylides excisus, p. 370. 



This key is a translation, with slight modifications, of the one 

 given by Jaegerskiold. 



EUSTRONGYLIDES TUBIFEX (Nitz.ch in Rudolphi. 1819) Jac*erskiold. 1909 



Synonyms. — Strongylus tubifex Nitzsch, 1819, part; Eustrongylus 

 tubifex (Nitzsch, 1819) Diesing, 1851, part; Hystrichis tubifex 

 (Nitzsch, 1819) Molin, 1861, part. 



Hosts. — Primary: Anas boschas dom-estica, Colymbus arcticus, C. 

 septentrionalis; secondary : Unknown, but fish probably (see below 

 3612—27 25 



