TWO NEW DIPLOPOD MYIIIAPODA OF THE GEXUS 

 OXYDES]\irS FKOM THE CONGO. 



By O. F. Cook. 



Neakly two years ago, I received from the U. S. National Museum a 

 small collection of Myriapoda, sent in by Ilev. J. H. Camp, of the 

 American Baptist Missionary Union. The Polydesmid;\; were repre- 

 sented by the two species of Oxydesmns here described. 



Since the specimens have been in my hands I have had opportu- 

 nity of comparing- them with the types of 0. afer (Gray) and 0. (jrayi 

 (Newport), in the British Museum, and with those of 0. irivu^pUlatHS 

 (Peters) in the Berlin Museam, with none of which are they identical or 

 closely related. As far as may be judged from the insufficient descrip- 

 tions of the other species, these Congo Valley forms offer a new character 

 in the great width of the ax)ex of the last segment. This, howevei-, can 

 hardly form the basis of generic distinction, for the other characters, 

 including those drawn from the copulatory legs of the nmle, otter merely 

 specific ditt'erences frcmi the other species of Oxydesmiis. Indeed, the 

 characters of the coiDulatory legs in the present genus are of compara- 

 tively little use in separating the species, the differences being so slight 

 as to be very diflicultof detinition, even between species strikingly dis- 

 tinct in color, sculpture, and form. 



The genera of Polydesmidic have in very few cases been adequately 

 described, so that their characters and aftinities must be inferred mostly 

 from what may be known of the typical species. In the case of Oxydes- 

 mus the species ditter little in structural cliaracters, and wliile the type 

 species, O.flavomarfiinatus, is not .sufficiently known, it was said by its 

 author to differ only in color from 0. tricuspidatus, so that a generic 

 description is apparently practicable. 



Genus OXYDESMUS (Humloert and Saussure). 

 Oxiidcsuiiin (Hu.AinEirr and Saussure), Xevh. Zool.-Bot. Ges. Wieii, 18(59, p. 671. 

 Diaynosis. — Body large. Antenmp with four olfactory cones. Seg- 

 ments dorsally with three transverse rows of rounded granules or 

 tubercles. Segments 1-4 without specially enlarged tubercles. Lateral 

 carime large, the lateral edge thin and sharp, even, or nearly so. 



ProceeiUuKs of the Tniied Statt's Naticiiial Museum, Vol. XVIII— No. 10:i(). 



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