MILLIPEDS OF PANAMA—LOOMIS 103 
represent another species. It is 5.5 mm. long and 1 mm. wide; 
tubercles of anterior row on segment 1 are larger than those of the 
second row or any of those on segment 1 in the male; on ensuing 
segments the tubercles of the primary rows are round and the two 
inner rows have two distinct rows of secondary tubercles between 
them. 
Family Vanhoeffeniidae 
Genus Cryptogonodesmus Silvestri 
Cryptogonodesmus Silvestri, Anal. Mus. Nac. Buenos Aires, ser. 2, vol. 6, p. 59, 
1898. 
Cryptogonodesmus species 
Numbers of females or young from the localities below are not 
identifiable as to species. 
Canal Zone, Barro Colorado Island, June 6, 1923, O. F. Cook 
and H. F. Loomis; March 8-15, 1958, E. M. and H. F. Loomis. 
Panama, Juan Dias, June 3, 1923, O. F. Cook and H. F. Loomis. 
Enantiogonus, new genus 
Type sprcies: Enantiogonus fragilis, new species, by present 
designation and monotypy. 
Driaenosis: Probably most closely related to Jrazunus Attems, 
of Costa Rica, the males of which have 19 segments, the females 20 
segments, but differing in the gonopods and possibly in the truncated 
preanal scale, which was not described for Jrazunus. 
DescrieTion: Body small, delicate, and poorly chitinized, re- 
sembling a tiny Polydesmus in appearance, composed of 19 segments. 
Head with margin of labrum scarcely emarginate, sides of head 
straight but oblique; antennae not especially slender, joints 2 to 6 
little different in length but joints 5 and 6 somewhat thicker. 
Segment 1 semicircular, narrower than ensuing segments, en- 
circled by 16 erect setae, 8 near anterior and 6 near posterior margin 
and 1 in each outer angle; there are 4 additional setae across middle 
of disk. 
Ensuing segments with three transverse rows of setae, apparently 
4-4-6 or 6-4-6, but so many are rubbed off this cannot be determined ; 
surface of segments finely reticulated and raised into large faintly 
polygonal areas; also there is a distinct transverse median impression ; 
lateral carinae thin with anterior corners rounded, posterior corners 
angular beginning with segment 2, those of segments 15, 16, and 17 
increasing rapidly in size but those of segment 18 greatly reduced; 
on all except the cadual segments the posterior margin between the 
produced angles is triarcuate; pores large, opening outward and 
