372 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



Esophagus 8 mm. long. Bursal cup (fig. 431 c and d) 290 to 350.x 

 long by 400 to 550/*. wide; no incision of margin on ventral surface 



Female 55 to 96 mm. long; maximum width 1.5 to 2 mm. ; width at 

 head end 250 to 400/a. Esophagus 11.6 to 16.4 mm. long. Eggs 58 

 to 66ti long by 35 to 44/* wide; shell 4.5ii thick, with pittings rela 

 tively sparse (fig. 431 e and /). 



Life history. — Unknown, involving intermediate stages in fish. 

 Jaegerskiold states that larvae found in Brasilian fishes by 

 Schneider and by Leuckart resemble this species and Chapin recently 

 (1926) has found the preadult stage of this species in Fundulus 

 diaplianus at Washington, D. C. In a large number of fish exam- 

 ined by Chapin, each fish contained one to three specimens of the 

 nematode, the adult characters of which could be seen within the 

 last cuticle, corresponding exactly to those of adult worms found by 

 him in Ardea herodias, also at Washington, D. C. See also E. 

 tubifex, p. 367. 



Distribution. — Europe (Germany (Berlin) and Austria (Museum, 

 Vienna) ). 



EUSTRONGYLIDES MERGORUM (Rudolphi, 1809) Cram, 1927 



Synonyms. — Strongylus mergorwnv Rudolphi, 1809; Strongylus 

 papillosus Rudolphi, 1809, part; Strongylus elegans Olfers, 1816; 

 Strongylus tubifex Rudolphi, 1819, part; Tropidocerca paradoxa 

 Linstow, 1877 not T. paradoxa Diesing, 1851 ; Hystrichis elegans 

 (Olfers, 1816) Railliet, 1893, part; Eustrongylides elegans (Olfers, 

 1816) Jaegerskiold, 1909; Microtetrameres inflata (Mehlis, 1846) 

 Travassos, 1915 and its synonyms (p. 357). 



It is regrettable that the well-known specific name elegans should 

 have to be dropped but Rudolphi's name clearly antedates it and is 

 not a nomen nudum, having a brief description by him, based on a 

 description and figure by Redi. 



Hosts. — Primary : Alca torda, Anas hoschas domestica, A. glacialis, 

 A. mollissima, Charadrius pluvialis, Ciconia nigra, Colymbus septen- 

 trionalis, Harelda glacialis, Merganser serratus, Mergus albellus, M. 

 merganser, M. serrator, Numenius arquatus, Phalacrocorax carbo, 

 Prodiceps cristatus, P. minor, Somateria molisswia, TJria troile; 

 secondary : Unknown ; probably fish, according to Jaegerskiold and 

 to Ciurea. See E. tubifex, p. 367, and E. ignotus, p. 371. 



Location. — In tubercles in the esophagus and pro vent riculus. 



Morphology. — Eustrongylides (p. 367) : White, thick fusiform 

 worms, attenuating at the 2 extremities. The head end (figs. 432 and 

 433) is elongate piriform, connecting by a slender, neck-like part 

 with the middle portion of the body, in some adults. About the 

 mouth is a circlet of 6 lateral and submedian papillae, and outside of 



