118 DIPLOPODA. 
Subfam. CYCLODESMIN. 
The two Central-American genera belonging to this subfamily may be distinguished 
as follows :— 
a. Segments with transverse crests surmounted with a series of tubercles ; 
fourth segment about equal to the third in size. . . . . . . . . « CyPHopEsmus. 
a'. Segments smooth, without crests and tubercles; fourth segment much smaller 
than the third, which greatly exceeds the rest . . . . . . . . . « CycLopEsmus. 
CYPHODESMUS. 
Oniscodesmus, Saussure, Mém. Soc. Phys. Genéve, xv. p. 278 (1860) (nec Oniscodesmus, Gerv.). 
Cyphodesmus, Peters, Mon. Ak. Wiss. Berlin, 1864, p. 580; Cook, Pr. U.S. Nat. Mus, xxi. p. 466 
(1898) ; Attems, Denk. Akad. Wien, lxviii. p. 390 (1890). 
This genus appears to have been examined only by the original describers of the 
typical and single known species. 
Body comparatively narrow and elongated, convex and vaulted, but with the keels slightly inclined outwards ; 
* each segment with a transverse row of erect tubercles, larger on the summit than laterally. When the 
body is extended the keels are not in contact. First tergal plate much wider than long; the second 
crescentic, and with the keels but little extended laterally ; third and fourth large and subequal; anal 
tergal plate relatively large subquadrate, with four large tubercles. 
Secondary sexual characters unknown. 
Distribution. Mexico. 
1. Cyphodesmus mexicanus. 
Oniscodesmus mexicanus, Sauss. Linn. Ent. xiii. p. 328 (1859)'; Mém. Soc. Phys. Genéve, xv. 
p. 281, t. 1. fig. 2 (1860) *. 
Cyphodesmus mexicanus, Peters, Mon. Ak. Wiss. Berlin, 1864, p. 580°; Sauss. & Humb. Miss. 
Sci. Mex., Myr. p. 23 (1872)*; and of subsequent authors. 
Colour fuscous ; integument finely granular. Head smooth ; antenne with subequal segments. First tergal 
plate with three tubercles on each side; second with five. TZhird segment with its keels strongly arched 
and sinuous, its anterior angle rounded and the posterior acute and directed backwards; marked with 
a crest, which becomes obsolete above; keels of the fourth large, inferiorly rounded, but with the 
posterior angle a little produced. Inferior margins of keels of the mid-region of the body rounded ; 
those from the thirteenth segment backwards truncate and wide inferiorly. The tubercles borne upon 
a transverse crest, which is higher on the fifth segment than on the others, On the seventeenth and two 
following segments the dorsal tubercles become spiniform. 
Length 20 millim., width 5. 
Hab. Mexico, Cordova 1~4. 
CYCLODESMUS. 
Cyclodesmus, Saussure & Humbert, Rev. et Mag. Zool. 1869, p. 149; Miss. Sci. Mex., Myr. p. 2 
(1872), and of subsequent authors. 
Surface of segments smooth and polished. Dorsum very convex; keels vertical, broad and subcontiguous. 
