MILLIPEDS OF PANAMA—LOOMIS 101 
side; antennae short, clavate, joint 5 twice as long as any other joint 
and slightly thicker, a long seta projecting from the upper side and 
a similar one on joint 6. 
Segment 1 of much the same shape as in Tracheloaspis, the expanded 
front margin somewhat reflexed, divided into 12 areas with anterior 
border faintly crenate; median area with 10 large rounded tubercles 
in 2 transverse rows. 
Ensuing segments each with four longitudinal rows of three tuber- 
cles each that are transversely oval; almost no secondary tubercles 
between the two inner rows but they are separated by a narrow deep 
groove; secondary tubercles between the inner and outer rows usually 
three, arranged in a triangle pointing forward; lateral keels from seg- 
ment 2 to 18 three lobed, the poriferous tubercle produced from the third 
lobe of segments 5, 7, 9, 10, 12, 13, 15, and 16, being large and sub- 
conical with the pore opening from just beyond middle of its upper 
side. Segment 19 with outer margin smooth and continuous, lacking 
crenations. Last segment rather long, parallel sided and with three 
strong terminal lobes which are concave below; dorsal surface with a 
broad median ridge continuing along the median lobe. 
Gonopods with hemispherical basal joint from which the inner or 
terminal joint projects but slightly. Male with joint 2 of third 
legs showing secondary modification. 
Xenoporus carinaceps, new species 
Figures 4f-g, 5a 
Hoxtotyre: Male, USNM myriapod collection 2643, El Valle, 
Panama, March 22-23, 1958, E. M. and H. F. Loomis. 
Paratype: Female, author’s collection, same collection data as 
holotype. 
Description: Body about five times as long as wide, 4.2 mm. 
long, 0.9 mm. wide. 
Head with clypeal and frontal areas shining, sparsely setose; 
vertex separated from front by a transverse depression on a line 
with tops of the antennal sockets, a distinct median impression 
present, surface finely granular, each side with a prominent granular 
ridge beginning behind each antenna and extending outward obliquely 
to back of head. 
Segment 1 with median area convex, crossed by two rows of rounded 
tubercules, four in front row and six in the back row following the 
curve of the posterior margin, the outer tubercle on each side smaller 
than the other eight. 
Ensuing segments with dorsum strongly convex, keels low on 
the sides, projecting outward and slightly downward; dorsal surface 
