Occasional Papers of the Museum of Zoology 55 



becoming larger and projecting more and more caudad. The 

 pore-bearing prominence also comes to project caudad in the 

 more posterior segments. (See PI. 20, Figs. 137 and 138.) 



Dorsal surface of metazonites in general but weakly con- 

 vex, densely granular, a transverse furrow but weakly devel- 

 oped, two rows of a few more prominent, apically darker, 

 granules behind this furrow. Sides of metazonites more finely 

 granular. Sterna with granules still finer, largely obsolete, 

 and sparer, in part becoming short setae. Spines at bases of 

 legs all very short. (See also PI. 20, Fig. 139.J 



Cauda proper with two setae on rounded tubercles on each 

 lateral margin and a pair on dorsum at base. (PI. 20, Fig. 

 138.) Anal scale with caudal margin convexly rounded, a 

 long seta on each side. (PI. 21, Fig. 140.) Anal valves 

 mesally margined. 



Legs with proximal joints granular. Last joint propor- 

 tionately very long. Claws well developed. (For proportions, 

 etc., see PI. 21, Fig. 141.) 



Length, about 30 mm. ; width, 4.2 mm. 



Colombia : San Lorenzo. One female taken under a stone 

 in a damp creek bed at 4,500 feet; July 3, 1913. Holotype, 

 M. C. Z., 5.144. 



Colombodesmus lygrus, sp. nov. 

 }'l. 21, Figs. 142-144 



This is a darker form than the preceding one, the general 

 color of dorsum and sides being a dark or dusky brownish 

 grey, the poriferous processes alone being lighter, fulvous. 

 Venter paler. Legs proximally white or fulvous white, dis- 

 tally brownish, the light color extending typically to or a little 

 beyond middle of femur. Antennae dark excepting at tip. 



The keels in general form and dentitions similar to those 



