CRYPTURODESMUS.—SPH ARIODESMIDA. 117 
Crypturodesmus a subgenus of his later-described Trigonostylus; whereas if the type- 
species of the two be congeneric, the genus must take the name Crypturodesmus, 
with Trigonostylus as one of its subgenera, and Crypturodesmus, repeated, as the 
other. It appears to me, however, that the distinctive features of the two are worth 
full generic value. TZrigonostylus, which has hitherto been recorded only from 
Venezuela, differs from Crypturodesmus in having the nineteeuth segment normally 
constructed. 
1. Crypturodesmus targionii. 
Crypturodesmus targionii, Silvestri, Boll. Mus. Torino, xii. no. 277, p. 1 (1897) ’. 
Colour reddish-brown, paler beneath. Head with the antenna short and incrassate, the fifth segment the 
largest, the seventh and eighth the smallest. Tergal plates granular, furnished above with four 
longitudinal rows of tubercles. First tergal plate semicircular; keels of the second very wide, with 
rounded, somewhat forwardly projecting anterior angle, the posterior angle acute; succeeding keels 
entire, the postero-latera] angle with a rectangular incision. Pores undiscovered. Anal sternal plate 
semicircular, 
Length 28 millim., width 5. 
Hab. Mexico}. 
Fam. SPHAERIODESMIDZ. 
Body strongly convex, capable of being spherically coiled, the keels vertical or nearly so, with their lateral 
borders inferior. Head absent. Tergal plate of the twentieth segment quadrate, surrounded anteriorly 
and laterally by the subcrescentic tergal plate and keels of the nineteenth segment. Hither the third or 
the fourth or the fourth and fifth segments laterally expanded and exceeding in size the corresponding 
portions of the succeeding segments. The second segment always small and embracing the first like a 
collar, 
Distribution. Southern States of N. America; Central America; West Indies. 
I include in this family the genera which Cook referred to the Spheriodesmida, 
Desmonidee, and Cyclodesmide, because the genera Spheriodesmus and Cyclodesmus 
appear to be linked to a certain extent by Cylionus, and because the essential feature 
upon which the Desmonide were separated from the Cyclodesmide is not known to 
occur in the one Central-American genus, Cyphodesmus, referred by Cook to the 
Desmonide. Nevertheless, the genera in question may be conveniently classified in 
two subfamilies :— 
a. Keels of third segment much smaller than those of the fourth, which are 
always larger than those which follow the fifth segment, and sometimes 
larger, sometimes a little smaller, than those of the fifth. . . . . . SPH#RIODESMINA. 
a’. Keels of the third segment larger than those of the rest of the series, rarely 
equalled by those of the fourth ; keels of the fifth not enlarged . . . CycLopDESMINE. 
