100 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 113 
Ficure 4.—a, Psochodesmus crescentis, posterior and slightly mesal view of left gonopod. 
b-e, Tracheloaspis tumida: b, Antenna; c, segments | and 2, dorsal view; d, last segment, 
anal valves, and preanal scale, ventral view; ¢, right gonopod, lateral view. f-g, Xeno- 
porus carinaceps: f, Lateral keel of segment 15; g, segments 18, 19, and 20, ventral view. 
mary ones well exposed. Last segment with marginal lobes as shown 
in figure 4d, in which the valves and preanal scale are also shown. 
Gonopods shown in figure 4e. Anterior male legs and sterna 
without modifications. Females with a high, slightly rolled crest 
or lip behind second pair of legs. 
Xenoporus, new genus 
TypE spEcins: Xenoporus carinaceps, new species, by present 
designation and monotypy. 
Diaenosis: Probably most closely related to Gasatomus Chamber- 
lin but differing particularly in having the pores opening from upper 
side of the pore tubercles and in the form of the gonopods. Dis- 
tinguished further by the unlobed margins of the keels of segment 19 
and the strongly concave ventral surface of the lobes of segment 20. 
Description: Body small and about five times as long as broad, 
dorsum strongly convex with broad keels from low on the sides. 
Head covered by segment 1; vertex with a granular ridge on either 
