844 



Pomona College Journal of Entomology 



and the /. besselsii (Packard) l)ut with apparent differences. They resemble 

 the /. minima perfectly except for the position of the teeth on the inucrones. 

 Because of this important difference I have provisionally classified mine as 

 /. besselsii. 



Length .75.1 mm. Color — Prown, yellow at junction of segments, fur- 

 cuhi and legs light ; ventral side dark. Body — Subeylindrical, sparsely 

 haired. Head — Elongate. Antenna' (A) about as long as head, segments 

 four; I shortest, IV longest, II and III subequal ; different from those de- 

 scribed by Macgillivray. "First and second segments dilated, as broad as 

 long and twice as broad as tlie tliird or fourth." In my specimens, I is as 



Figure 270. Isotoma besselsii Packard, A to D. 



A, antenna; B, claws; C, denies and niucrones; D, mucrones; E, niucrones of 



I. minima, after Guthrie. 



broad as long, l)ut tliis is not true of II. Also I and II are not as broad as 

 III and IV. Ocelli, si.xteen. Thorax — Segments not fused. Joints of legs 

 same as /. bidenticula; tenant hairs on tibia; claws (B) uncurved; superior 

 claw wide at the base but narrow at the apex ; inferior claw with inner 

 margin dilated at base. Abdomen — Segments sul)e(iual; IV, V and VI 

 appear to be fused. Furctda short, stotit, not reaching ventral tube ; manu- 

 ])rium slightly longer than dentes; mucrones (D) tridenticulate ; distal tooth 

 long and but little curved; second and third teeth of about the same length, 

 vertical, on ojjiiosite sides of the muctrones and nearly opposite each otlier. 



