III. 
THE GENERA OF OXYDESMID.®. 
An analytical key to the genera of this family was published some 
months since but the study of more extensive and better material 
has led to the recognition of several new generic groups. The 
family has also been limited by the separation of some of the forms 
previously included, these being assigned to a new family called Pre- 
podesmidae t- The diagnostic characters of the genera now recog- 
nized are indicated in the following table, to which is appended a list 
of the species. A monograph of the family will appear in a few 
months. 
KEY TO THE GENERA OF OXYDESMIDA5. 
Dorsum densely beset with 4 to 6 transverse rows of coarse tubercles : 
Genus Scytodesmus Ck., Kamerun. 
Dorsum smooth, granular, or with three rows of polygonal areas, each with 
a large tubercle in the middle. ......... 
Submarginal ridge very oblique, broad and not prominent, remote from the 
margin ; pores in a broad, shallow’- depression in the middle of the ridge, hence 
also remote from the margin : Genus Plagiodesmus Ck., Congo Valley. 
Submarginal ridge nearly or quite longitudinal, parallel with and adjacent 
to the margin ; pores also not remote from the margin, located in the outer 
slope of the submarginal ridge 
Apical margin of last segment transverse and very broad, the lateral mar- 
gins parallel, convex, or divergent caudad ; apex proper also very broad, equal- 
ing in width the four setiferous tubercles, which are also located on the poste- 
rior margin and are not greatly exceeded by the apex : Genus Lacnodesmus, 
nov., type Z. campu Congo Valley. 
Apical margin of last segment more or less rounded or triangular in general 
outline, the lateral margins more or less converging caudad; apex proper dis- 
tinctly narrowed and exceeding the tubercles, one or both pairs of which 
appear to rise from the lateral margin : the posterior marginal tubercles at 
least projecting much farther caudad than the anterior, except in certain East 
African forms where the tubercles are greatly developed 
Dorsum smooth and shining ; under a lens finely rugulose or coriaceous ; no 
granules, tubercles or areas: Genus Mimodesmus Ck., East Africa. 
Dorsum with more or less conspicuous granules, tubercles, and areas. . . 
Segments with the tubercles not specially modified or increased in size ; 
copulatory legs bent at the middle of the last joint, and the apices inserted 
under the anterior edge of the large aperture : Genus Oxydesmus (H. & 
S.), West Africa. 
Segments 1-4. or some of them, with at least the median posterior tubercles 
hypertrophied ; copulatory legs extended and exposed 
*Proc. U. S. Nat. Mus. XVIII, p. 99, 1895. 
t American Naturalist, XXX, p. 415, 1896. 
Brandtia, p. 9. 
