new Siamese Nematode. 415 



Hub. Gut of Chelonia. 



Genotype: F. \Oxysomd\ fahata (v. Linst., 1906), from 

 Geoemyda \_Nicoria\ trijuga. 



Note on the Systematic Position 0/ Falcaustra. 



At first sight it would not seem unnatural to include the 

 species just described in the subfamily Subulurimc of the 

 family Heterakidse, on the ground of the presence of proanal 

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

 myarian musculature, the position and character of the excre- 

 tory pore, the structure of the oesophagus with its two bulbous 

 expansions posteriorly, and the fact that suckers do not occur 

 in the genotype render this classification 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 meromyarian forms, 

 such as " Oxysomatium' n lepturum (Kud.), from Chelan e 

 my das. The presence of a preanal sucker or suckers, there- 

 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 Oxyurida?, 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 position, and means little more than 

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

 defined. 



The further question arises whether Falcaustra should not 

 be grouped with Kathlania, Lane, 1914 (= Oxysoma of 

 iSchneider, 1866, in part), a genus occurring in turtles, and 

 possessing, like the iSubulurina?, a preanal sucker in the males. 

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

 Kathlauiina?, which is practically identical with the Subulu- 

 rinse of Travassos, 1914, of the Heterakidee. Barreto (1919) 

 excludes Kathlania from the Subulurinse *, and points out 

 that its position among the Heterakidse would depend upon 

 the type of its subcuticular musculature, which has not been 

 described. An examination of the origiiral specimens of the 

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

 lature is of the same type (meromyarian) as in Falcaustra. 

 It would seem justifiable, therefore, to remove Kathlania, as 

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

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



* There appears to be a discrepancy on this point between the original 

 and the English translation of Barreto's paper, owing to the omission of 

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



