82 University of Michigan 



Agnurodesmus thrixophor, sp. nov. 

 PI. 30, Fig. 212 



Dorsum brown over fulvous, the brown pigment on each 

 metatergite tending to outline roughly two transverse rows of 

 l)olygonal area. Venter and legs fulvous. 



Collum with anterior margin straight ; the caudal and lat- 

 eral margins together forming a convex or semi-circular curve. 

 Across the anterior border a series of longitudinal sulci, leaving 

 between them ridges or elongate tubercles, each of which bears 

 a seta; this series of tubercles continues out upon the lateral 

 lobe or keel, but shifts a little caudad, the tubercles being 

 shorter and more remote from the anterior margin. Back of 

 this anterior series of ridges the surface bears numerous shorter 

 setae. (PI. 30, Fig. 212.) 



The second tergite is long, bent downward and expanded 

 l)elow, the lower margin attaining the lower level of head and 

 the anterior rounded corner protruding forward also as far 

 as the anterior edge of the head or nearly so. Lateral margin 

 with ten crenations, the first being the much larger rounded 

 anterior corner. Caudal margin notched somewhat as in Clio- 

 desmus, Init the notch larger and more oljtuse. Keel margined 

 all the way around. 



The third tergite with keel much shorter, only four crena- 

 tions on ectal margin. Caudal border concavely excavated for 

 reception of succeeding keel. In the following segments the 

 anterior margin smooth and straight, or nearly so, the mesal 

 angle jutting forward as usual. Four crenations at ectal end 

 of fourth to sixth keels, usually five on the others or six on a 

 few of the last ones. Within the margining rim all around, 

 or more vaguely on anterior border, a series of areas sepa- 

 rated bv sulci or depressions, each one bearing a seta; the 



