1922.] H. A. Baylis and R. Daubney : Parasitic Nematodes. 297 



regards it as related rather to the Oxyuridae than to the Heterakidae. His contention is based chiefly 

 on the characters of the lateral fields and of the body-muscles. The other points mentioned (presence 

 of lateral aiae on the body, absence of caudal alae in the male), are clearly not universal characters of 

 Strongyhiris as at present constituted. Un the other hand, the structure of the preanal sucker, which 

 is exactly similar to that of Heterakis, is a character probably quite as important as the lateral fields • 

 while the arrangement of the musculature does not appear in all cases to be a reliable guide to clas- 

 sification. Travassos, in a recent paper (1920 [?] ) has suggested placing Strongyluris in anew subfamily, 

 Spinicaudinae, of the Heterakidae. Railliet and Henry (1914), regarded it as a subgenus of Heterakis. 

 We prefer to treat it as a genus, with close relationships to Heterakis, and reserve judgment on the 

 question of including it in a separate subfamily. The following tabular arrangement of the species 

 shows that there are two well-marked groups within the genus as hitherto constituted, these groups 

 being characterized chiefly by the presence or absence of caudal alae in the male. 

 A. Tail of male without alae. 



a. Tail long, straight and tapering. An accessory piece present. 



S. sonsinoi (v. Linst., 1894). 

 S. campanula (v. Linst., 1899). 



8. icosiensis, Seurat, 1917. 



b. Tail obliquely truncate ventrally, but with an elongate 

 terminal cone. An accessory piece present. 



B. Tail of male with bursa-like alae and obliquely truncate. 

 Accessory piece absent. 



S. brevicaudata, Müller, 1894. 

 S. paronai (Stossich, 1902). 

 S. elegans (Gendre, 1909). 

 S. chamaeleonis, sp. nov. 



S. ornata (v. Linst., 1897) and S. streptoesophageus , Connal, 1912, are probably synonymous 

 with 8. brevicaudata. 



It seems justifiable to restrict Strongyluris to the forms (B) which agree with its genotype, 

 S. brevicaudata, in the characters mentioned ; while we propose to erect a new genus, Sonsinia, to 

 include the non-alate forms, with 8. sonsinoi as genotype. 8. icosiensis appears to occupy a somewhat 

 intermediate position, but for the present may be referred to Sonsinia. 



Genus Pseudaspidodera, nov. 



Pseudaspidodera pavonis, sp. nov. 



(Figs. 34-37.) 



Hosts: Burmese peafowl (Pavo muticus) and "white peafowl" (Pavo cristatus). 



This is a small worm, the male measuring about 6 mm. in length, the female 7 

 mm. The greatest thickness is about 0-25 mm. in the male, 0-3 mm. in the female. 

 The cuticular striations, if present, are too fine to measure. The head (fig. 34) is 

 ornamented with "cordons" resembling those of Aspidodera, opening in pairs at the 

 interlabial spaces, and consisting of tubular grooves running below the surface of the 

 cuticle, with a narrow external opening along their length. The members of each 

 pair of cordons diverge at once and, after running back for a short distance, turn 

 forward, each on to the outer surface of one of the three lips, where, instead of joining 

 the corresponding member of the next pair, as in Aspidodera, it ends separately. The 

 diameter of the head at the posterior limit of the cordons is about 01 mm. Narrow 



