86 DIPLOPODA. 
4. Cyclothyrophorus vulvanus. 
Spirobolus vulvanus, Karsch, Zeitschr. ges. Naturwiss. (3) vi. (liv.) p. 55 (1881). 
Colour black, with the posterior borders of the tergal plates flavous. 
Head nearly smooth, with 3 or 4 labral pores on each side; area between the antenne impressed. First tergal 
plate with its lateral portion extending inferiorly as far as that of the second, narrowed, subacute, the 
anterior margin excavated and defined by a sulcus. The rest of the segments with the transverse sulcus 
not deep; the median portion very finely subrugose, sculptured with longitudinal strie and scattered 
punctures ; inferiorly striate, posterior portion slightly convex, sulcate beneath, sparsely impressed with 
punctures, marked with a median dorsal sulcus and a lateral sulcus behind the pore, which is placed 
behind the transverse sulcus. Anal segment punctured; tergal plate widely rounded; valves strongly 
convex, vulviform. 
Number of segments 43. Length 30 millim, 
Hab. Mexico, Puebla (Berckenbusch). 
So far as can be judged from the description, this species is very nearly related to 
S. nietanus. The form of the first tergal plate is not very, if at all, different in the 
two, and the conformation of the anal valves appears to be the same—that is to say, 
they are convex with the margins uncompressed and forming a re-entering angle where 
they meet, so as to conform to the type that Karsch described as “ vulviform.” In size 
and number of segments the two species are also alike. Unfortunately Karsch says 
nothing about the secondary sexual character of the male, although both sexes were 
available for examination. C. vulvanus appears, however, to differ from C. nietanus at 
least in the distinct sculpturing of the tergal plates. 
SPIROBOLELLUS. 
Spirobolellus, Pocock, in Max Weber’s Zool. Ergebnisse einer Reise in Niederl. Ost-Ind. 1894, p. 398. 
For characters, see infra, p. 89. 
This genus was based upon a single species, S. chrysodirus, from Sumatra. It is 
possible that the Central-American forms here referred to it may prove to be generically 
distinct ; but until a revision of all the genera of this family has been taken in hand, 
I prefer to assign to Spirodolellus the three species described below. These may be 
distinguished as follows :— 
a. Larger, length up to or over 50 mm.: sculpturing very coarse and pitted ; 
a well-developed caudal process; posterior lamina of coleopod entire 
inferiorly ; first tergal plate very wide laterally, with the thickened ante- 
rior border largely overlapping the base of the mandible . . 
a‘. Smaller, length only up to about 40 mm.: sculpturing comparatively weak ; 
no caudal process; posterior lamina of coleopod deeply emarginate 
below, cut out into an outer stout and an inner slender more styliform 
process ; first tergal plate much narrower laterally, and its anterior 
border less thickened and not concealing the basal segments of the 
mandibles. 
richardsoni, sp. 0. 
