Occasional Papers of the Museum of Zoology 41 



Spiroboleli-idaf, 



Microspirobolus tridens, sp. nov. 



PI. 16, Fig. 109; PL 17, Fig. no 



Dorsum fulvous to buff, with a middorsal Ssripe formed by 

 a series of black triangular marks with bases cephalad, the 

 lateral angles extending laterad in black lines along anterior 

 borders of the somites to unite with the black band along each 

 side. A'enter and lower part of sides again light colored 

 excepting borders of segments. Last tergite black, excepting 

 a light spot anteriorly on each side. Collum also blackish, 

 excepting a pale spot on each side behind. Legs ferruginous. 



Eyes about equal in length and breadth. Ocelli about 18 

 in only four series ; c. g., 5, 5, 5, 3. Eyes separated by a space 

 three times as long as their diameter. Antennae very small. 



Collum narrow^ed moderately down each side, the lateral 

 ends rounded and bent a little mesad below ; margin below 

 and up the front as usual. 



Each ordinary segment with a moderate encircling furrow 

 or constriction ; this crossed by numerous ridges or ribs both 

 on dorsum and down the sides, the depressions between the 

 ridges on the sides continuing upon the prozonite as deep 

 striae which curve upward. Metazonite striate below. 



Last tergite rounded caudally, projecting caudad freely 

 above valves for a short distance. Anal valves weakly mar- 

 gined along mesal edges, the borders not protruding. 



Characterized especially by the form of the gonopods of 

 the male, which are represented in PI. 16, Fig. 109, and PI. 

 17, Fig. no. 



Number of segments, 34 to 37. 



Length, about 18 mm. ; width, to 2 mm. 



Colombia: San Lorenzo; 4,500 feet; July 3, 1913. Four 



