MILLIPEDS OF PANAMA—LOOMIS 89 
First segment quadrangular, front margin smooth, lacking the 
irregularities shown in Cook’s figure 2d for L. rubriceps, almost 
straight and longer than posterior margin, which is convex and over- 
laps segment 2; anterior corners rounded, deflexed slightly and with 
a strong, thin, raised rim; surface considerably behind front margin 
with a prominent biarcuate sulcus nearly reaching the sides and more 
impressed on either side than at middle; surface on either side behind 
the sulcus smooth but evenly inflated; posterior margin faintly areate, 
with short sulci. 
Segment 2 (fig. 2c), compared with that of L. rubriceps, not pro- 
duced downward as far, scarcely exceeding segment 3, the side more 
expanded forward, the lower posterior corner less produced back- 
ward. On succeeding segments the surface in front of the areate 
portion is more convex than the areate border but on posterior end of 
body both portions are flatter and the areations less evident. Pores 
borne on low rounded elevations on segments 5, 7, 9, 10, 12, 13, and 
15, a very slightly raised swelling on segment 16 with the pores of 
17 and 18 opening from the level surface. Posterior end of body 
shown in figure 2d. Last segment thick and strongly convex, broadly 
rounded behind and, in ventral view, the margin with a small rounded 
lobe on either side of the median portion. 
Female with ventral margin of segment 3 raised at middle into a 
triangular lobe. 
Panamadesmus, new genus 
Type sprectes: Panamadesmus sculptilis, new species, present 
designation and monotypy. 
Draenosis: Probably most closely related to Mesesmus Cham- 
berlin but differing as stated below. 
Description: Body the shape and size of Lignydesmus Cook and 
Mesesmus Chamberlin and with pores borne in similar manner—but 
readily distinguished by the much more definitely sculptured first 
segment, which is emarginate in front; the almost completely closed 
sinus of segment 19, hiding segment 20 from above; the erect gono- 
pods of which the outer division ends in a mesally concave spoonlike 
expansion, the inner division being stout, straight, and bluntly point- 
ed; joint 3 of third male legs distally swollen, whereas no such modi- 
fication of the male legs has been reported for Lignydesmus, and no 
males of Mesesmus are known. The genus differs further from Me- 
sesmus in having segment 2 descending considerably below segment 
3 instead of scarcely exceeding it as shown in Chamberlin’s illustra- 
tion. Last segment considerably exceeding anal valves with a small 
seta-bearing lobe on cither side and several subapical ones. Preanal 
scale with two seta-bearing subapical tubercles, sides concave. 
