— 139 — 



three Nematodes: Oxysoma brevicaudata Z e d. (from Rana 

 temporar'ia), Oxysoma tentaculiim R ii d. (from Didelphis) and 

 Oxysoma lepturum Rud. (from Testudo mydas) which are to 

 be considered at present as representatives of three different 

 famiUes! 



The chief species on which Schneider founded his ge- 

 neric diagnosis — Oxysoma brevicaudata Zed. — is the type of 

 this genus, on account of which only such Nematodes must 

 be referred to Oxysoma, which are united by common cha- 

 racters with the parasite Oxysoma brevicaudata. 



There are but few of such Nematodes from the number 

 described under the name Oxysoma; they are: Oxysoma con- 

 tortum hi w si o\s 1906 (from Bufo vulgaris) and Oxysoma 

 perezi Gendre 1911 (from Chamaeleo gracilis Hall.). These 

 parasites must be considered as the real representatives of 

 the genus Oxysoma. 



As concerns the other species — Oxysoma gracilis L ins tow 

 1899 (from Francolinus sp.) came out to belong to the genus 

 Subiilura ]\Iolin, as was shown by Railliet et Henry in 191-1; 

 Oxysoma falcatum Linst. 1903 (from the turtle — Nicoria 

 trijuga), as well as Oxysoma tuberculatum L i n s t o w 1903 

 (from Megaloplirys montana Wag.) must also be separated 

 out of the genus Oxysoma, on account of the peculiar struc- 

 ture of the spicula and caudal extremity of the male. 



When looking through the descriptions of species of the 

 genus Nematoxys Schn. 1866, which is allied to Oxysoma, 

 I came upon one form — Nematoxys unguiculatus Linst. 

 1906 (from Bufo viridis], which must absolutely be referred 

 to the genus Oxysoma, being very closely related to the spe- 

 cies Oxysoma contortum Linst. (from Bufo vulgaris). After 

 reading the description of these two forms given by the same 

 author in the same year, and even in the same work on 

 adjoining pages (pp. 255 and 256), it is difficult to understand 

 what induced the author to refer them to two different ge- 

 nera {Oxysoma and Nematoxys)'! The only difference between 

 these forms lies in the measurements of the different organs, 

 though even these fluctuations in the size of the latter are 

 found only in the tenth parts of a millimeter! 



These facts serve as an eloquent illustration of how diffi- 

 cult it is to classify the representatives of those Nematodes, 

 the generic diagnoses of w^hich have not yet been re-exa- 



