neio Siamese Nematode. 415 



Hah. Gut of Clielonia. 



Genotype: I^\ [O.i'i/so))ui] /areata (v. Linst., 1906), from 

 Geoemyda \_Nicoria'\ trijuga. 



Note on the Systematic Position r)/Falcau.stra. 



At first siglit it would not seem unnatural to include tlie 

 species just described in the subfamily Subulurina; of the 

 family lleterakida^, on the ground of the presence of proanal 

 suckers, without chitinoid ring, in the male. But the mero- 

 myarian musculature, tlie position and character of the excre- 

 tory pore, the structure of the oesophao-us with its two bulbous 

 expansions posteriorly, and the fact that suckers do not occur 

 in the genotype render this chissification improbable. 



Railliet and Henry (1916, a) are inclined to place Falcaustra 

 among the Oxyuridse, and they have pointed out (1914, p. 674, 

 footnote) that a sucker occurs in certain mcromyarian forms, 

 such as '' O.vy solatium ^' lepturam (Rud.), from Chelone 

 mydas. The presence of a preanal sucker or suckers, tliere- 

 fore, is not a certain indication of Heterakid affinities, and it 

 should be noted that in the present case it is clearly not even 

 of generic value, since one species possesses suckers, while the 

 other does not. 



The family OxyuridsB, at present, stands in need of more 

 precise definition, and, if Falcaustra be assigned to this family 

 provisionally, it should be clearly understood that this leaves 

 it in a quite unstable jiosition, and means little more than 

 that it is not referable to the Heterakida?, as at present 

 defined. 



The furtlier question arises whether Falcaustra should not 

 be grouped with Kat/ilania, Jjane, 1914 {=O.Vi/soma of 

 Schneider, 1866, in ])art), a genus occurring in turtles, ami 

 possessing, like the ^Subulurinai, a |)reanal sucker in the males. 

 Lane (1914) proposed this genus as the type of a subfamily 

 KathlaniiuEe, which is practically identical with the Siibulu- 

 rina3 of Travassos, 1914, of the Jleterakidae. Barreto (1919) 

 excludes Kathlania from the yubulurinai *, and points out 

 that its })Osition among the Ileterakidie would depend upon 

 the type of its subcuticular musculature, which has not been 

 described. An examination of the original specinnms of the 

 genotype, K. kaihlena, Lane, 1914, shows that the muscu- 

 lature is of the same type (mcromyarian) as in Falcautttra. 

 ]t would seem justifiable, therefore, to remove Kalhfauia, as 

 Barreto suggests, to the Oxyuridre, and further, in considera- 

 tion of the presence of a sucker and other points of resem- 



* There appears to be n discrepancy on tliis point between tlie orig-innl 

 and the I'jigli.'^li transhition of JJarreto's paper, owiiiy- to tlie omission of 

 a negutive in the latter. The sense of the original is here followed. 



