BY VERA IRWIN SMITH. 553 



The small worms found comprised two species of Nematodes, which, on super- 

 ficial examination, are very much alike, though belongring to two distinct families, — 

 TrichinelUdae and Tricltostrongylidae. Apparently, Nematodes of the latter family 

 are not at all common in pigeons . None were recorded until 1904, when Stevenson 

 found one species in considerable numbers in the intestines of a flock of fancy 

 pigeons at Washing-ton, and described it under the name of Strongylus quadri- 

 radiatus. He states that a single specimen contained in the helminthologieal col- 

 lection of the U.S. National Museum, which was collected by Hassall at Washing- 

 ton in 1892, belongs to the same species. I have not been able to find any re- 

 cords of later observations of this worm. All the more recent references' relate 

 to Stevenson's description. But examination of the specimens found here shows 

 them to be identical with Stevenson's species. 



In his original description, Stevenson observed that he retained, merely tem- 

 porarily, the generic name Strongylus (properly limited to the Sclerostomes), 

 pending an extensive revision of the whole gToup. By means of a diagnostic 

 table he compared the new parasite with the three species S. pergracilis, S. nodu- 

 laris, and S. tenuis, which he considered closely allied forms. In the following 

 year (1905) Loos established the genus Tricliostrongyluf to include four species 

 separated from the old genus Strongylus, and in 1909 Shipley added the species 

 Tr. pergracilis, Tr. nodularis, and Tr. tenuis, and suggested that Strongylus 

 quadriradiatus was possibly also a Trieliostrongylus. But Ransom (1911) pointed 

 out that Strongylus nodularis, and S. quadriradiatus differed widely from the 

 type, and should be excluded from the new genus, and in 1912 Neveu-Lemairc in- 

 cluded the latter in his work under the name Strongylus 1 qvadriradiatus, wjith 

 the note "Ce strongyle appartient certainement h la sous-famillie des Trieho- 

 strongylinae, mais le nom generique de strongyhis ne lui eonvient pas; sa de- 

 nomination n'est done que provisoire." 



Stevenson's species certainly does not belong to the genus Trichostrongylus, 

 outstanding differences from the type being the relative sizes and positions of 

 the bursal rays, the form of the spicules, and the vesicular swelling of the cuticle 

 of the head. Eight other genera have been included in the sub-family Tricho- 

 strongylinae, but the present species does not conform to the description of any 

 one of them. It thei-efore becomes necessary to establish for it a new genus, for 

 which I propose the name Cephalostrongylus. 



Superfamily STEONGTLOIDEA -Weinland, 1858. 



Family TRICHOSTRONGYLIDAE Railliet, 1915. 



< 



Subfamily TRICHOSTRONGYLINAE Leiper, 1908. 

 Genus C e p h a l o s t r o n « y l ii s, n.g. 



Generic diagnosis. — Cuticle enveloping cephalic end inflated to form a vesicu- 

 lar enlargement. Mouth simple, no papillae. Bursa bilobed, supported by six 

 paired rays and one median unpaired ray; the two ventral rays close together and 

 parallel, curved ventrally at the tips, thicker than any of the other rays ; the three 

 lateral rays arising from a common stem, but mutually divergent; externo-dorsal 

 ray thinner and shorter than the lateral rays, given off from the base of the 

 doi-sal ray; dorsal ray still shorter, but thicker, shortly bifurcated at the ex- 

 tremity, the outer branches being a little longer than the inner, each of which is 



