PAMMICROPHALLUS, —ZEUCTODESMUS. 185 
the first segment less than half the length of the second, the latter about half the length of the third 
(femur), the sixth (tarsus) shorter than the third, but longer than the fourth and fifth taken together. 
Generative orifice moderately large with rim a ittle raised. 
3. Shorter than the 2, but with the keels better developed and the legs thicker, the sterna and basal 
segments of the legs more hairy; tarsi of legs of anterior segments somewhat thickly padded below 
with short hairs. Coxe of the third pair with a forwardly directed tuberculiform tooth. Phallopods 
very short, slender, and retracted within the fossa, attenuated and slightly hooked apically ; posteriorly 
a little above the apex there arises a small tooth-like process which is sometimes represented by two 
smaller teeth. Orifice of fossa small, irregularly elliptical transversely ; with the anterior and posterior 
margins considerably raised, well separated from the sternal plate, bearing the ambulatory legs of the 
seventh segment. 
Length, 9, about 25 millim., width about 42. 
” Sy 18 ” ” 9 4, 
Hab. Mexico, Omilteme in Guerrero 8000 feet (Z. H. Smith). 
2. Pammicrophallus pictus, sp.n. (Tab. XIV. figg. 4-4 0.) 
Resembling the preceding in colour, but with the antenne darker. Closely allied to the preceding also in 
structure, but with the keels better developed and the margin less thickened, this difference being 
especially noticeable on those that bear pores. 
3. In general features resembling that of A. ornatus, but with the edge of the cavity of the phallopods 
strongly elevated behind, not elevated in front; the distal segment of the phallopods very wide, owing to 
the presence of a laminate crest on each side, the apex turned outwards and forwards, strongly compressed 
aud ending in a point. No distinct processes on the coxe of the third leg. 
Length, 9, about 23°5 millim., width about 4:5. 
” oi ” 22 ” ” ” 4, 
Hab. Muxico, Omilteme in Guerrero 8000 feet (HZ. H. Smith). 
ZEVUCTODESMUS, gen. nov. 
Antenne long, scarcely incrassate, second, third, and sixth segments subequal, fourth and fifth only a little 
shorter. Body broad, somewhat resembling superficially that of the stout species of Fontarta or somewhat 
Cryptodesmus-like. Keels large and depressed, overlapping, and, except just at the posterior end, 
inclined slightly forwards, with the anterior border convex, the anterior angle widely rounded, the posterior 
border lightly concave and the posterior angle acute, becoming gradually smaller and more and more acute 
and spiniform from about the 16th to the 19th; lateral edges of the keels thin but slightly margined, 
the margin thickened a little round the pores, which are normal in number and close to the edge and only 
a little way in front of the posterior angle; the thickened margin continued round the anterior edge of 
the keels. The posterior borders of the terga from the summit to the tips of the keels sinuous. 
Sternal areas moderately wide and long, markedly narrower behind than in front, the posterior border of 
each from the 5th to the 19th with a deep mesial notch, giving rise to a pair of stout, blunt, posteriorly 
directed subspiniform processes; a somewhat similar but much smaller and less conspicuous process at 
the base of the anterior pair; antero-posteriorly the two larger posterior processes become gradually 
larger and are approximated quite at the hinder end. Anal sternal plate wide, with convex, scarcely 
angular border and with the two setiferous tubercles a little removed from the edge. Anal tergal plate 
gradually narrowed, with truncate apex. Legs moderately long, the third segment longer than the sixth, 
which only exceeds by a little the fifth. 
Q. Generative orifice of average size, with raised margin. 
3. Phallopods minute, vertical, bisegmented, the basal segment (coxa) small, without spur and without 
seminal fossa; the distal segment apparently united to the coxa by an immovable joint and incapable of 
being flexed at right angles to it, terminating distally in two diverging branches, the subsidiary not 
BIOL. CENTR.-AMER., Diplop., December 1909. 2B 
