172 DIPLOPODA. 
DUOPORUS. 
Duoporus, Cook, Pr. Ent. Soc. Wash. iv. p. 402 (1901). 
Antenne slender, clavate, the sixth segment the broadest and longest, its length a little exceeding that of the 
second. Head smooth, prominent ; without sulcus. First tergal plate semielliptical, wider than the 
head, a little narrower than the second, its angles not produced. Segments not sulcate or sculptured, 
smooth, rather strongly convex. Keels moderately broad, inserted about the middle of the side, broader 
on the anterior than on the posterior segment; the posterior border concave and posterior angle acute, 
becoming sharply spiniform on the posterior segments ; anterior angle rounded, with very minute notch ; the 
margin entire, thin, and with very fine raised rim. Pores present only on segment 5; minute and lodged 
in a depression just inside the edge of the keel, which is not thickened. Caudal process subtriangular, 
with apex abruptly narrowed, truncated. Anal sternal plate nearly as long as broad, with rounded 
margin; tubercles obsolete. Sterna with a small conical spine at the base of each leg. Phallopod quite 
simple; distal segment unbranched, subfalcate, at right angles to the proximal, which is large, prominent, 
and subeylindrical. Genital processes of second leg of g sharp, conical, and directed posteriorly. 
Type and only known species, D. barretti, Cook. 
Distribution. Mexico. 
Cook makes no suggestion as to the systematic position of Duoporus. The only 
character mentioned in the diagnosis from which I can form an opinion on this point 
is the shape and position of the genital processes of the second leg in the male, which 
in being conical and sharp and projecting backwards from the posterior aspect of the 
coxee resemble these same processes in Lthachodesmus, Strongylodesmus, and other 
genera referred by Carl to the Rhachodesminge ; but there is no evidence that the 
coxal spur is missing. In the presence of two pores only on the fifth segment, 
Duoporus differs from ali known Central-American genera, except Stenodesmus, a 
genus in other respects totally distinct from it. 
Since only one species of this aberrant genus is known, it is difficult to decide what 
characters are of generic and what of specific value. No doubt some of those 
mentioned in the generic diagnosis will prove to be merely of specific importance 
when other species have been discovered. 
1. Duoporus barretti. 
Duoporus barretti, Cook, Pr. Ent. Soc. Wash. iv. p. 404 (1901)’*. 
Colour pale purplish (in alcohol). 
Length 12-14 millim., width 1-9-2. 
Hab. Mexico, Cuernavaca in Morelos }. 
STRONGYLODESMUS. 
Strongylodesmus, Saussure, Linn. Ent. xiii. p. 827 (1859) ; Mém. Soc. Phys. Genéve, xv. p. 537 
(1860) ; Saussure & Humbert, Miss. Sci. Mex., Myr. p. 55 (1872), and of all later authors. 
Antenne long and slender. Second tergal plate as wide as the following. Keels well developed, situated 
high on the sides, horizontal; lateral borders of the pore-bearing keels thickened, of the poreless keels 
hardly bordered. Pores upon segments 5, 7-19, near the edges of the keels, the latter with rounded 
angles, except those of the 17th to 19th segments, which are broad and spiniform. Caudal process of 
