22 c ^ Canadian Arctic Expedition, 1913-18 



Chsetotaxy: Tergites (PI. V, fig. 62) with setae on the posterior ring only, 

 these bristles short and weak, the marginal group lying in or close to the dark 

 lateral stripe, the outer one far removed from the inner pair. Bristles of the 

 disk single, one on either side of the median dorsal stripe. Lateral bristles with 

 two on the posterior ring, one on the anterior ring. Sternites (PI. V, fig. 63) 

 with no bristles on the anterior ring; posterior ring with two bristles on either 

 side of the median line and at about mid-length of the ring, the distal bristle 

 longest. Nearer the posterior margin and lying farther distad, three setse 

 almost in a line, rather closely approximated but each one in its own distinct 

 puncture, the proximal two longest, the distal one small and weak. 



Colouration: A beautiful larva (PI. IV, fig. 47), light yellow in colour, 

 the thorax and lateral margins of the abdomen dusky. Three interrupte^d 

 dark-brown stripes on the dorsum, on the ihdividual segments shaped as follows : 

 on the anterior ring the median mark is rectangular, in front not attaining the 

 segment preceding, connected at its caudal end with the lateral stripes which 

 are dotted with yellow, on the proximal edge clear-cut, laterally passing into 

 the dusky of the margins of the abdomen; , posterior ring of each segment with 

 three marks more irregular and diffuse. Sternites dull yellowish with an indis- 

 tinct irregular dusky square on the anterior ring, this dusky area with an arcuated 

 line of four oval spots across the anterior third and two larger yellow blotches on 

 the posterior two-thirds, one on either side of the median line ; on the posterior 

 ring of each segment the dusky marks are irregular, shaped somewhat like an 

 hour-glass. 



Spiracular disk (PI. IV, fig. 48) small, surrounded by six small lobes; dorsal 

 lobes very small but slender, slightly divergent; lateral and ventral lobes long 

 and slender, in some the lateral lobes notably shorter than the ventral pair; 

 inner faces of the lobes unmarked with darker. Ventral lobes with a few long, 

 sensory bristles at the apex; a single long bristle on the ventral face at about 

 mid-length; lateral lobes with a similar group of bristles near the tip and a 

 longer one on the outer face near the apex. Spiracles small, widely separated. 

 Gills six in number, small, slender, inconspicuous, the caudal pair longest, the 

 cephalic pair with a short lobule on the basal inner side so it appears there are 

 six gills of which four are long, two short. i 



I have no idea to which species this handsome larva belongs. This species 

 and the last are amongst the most beautifully patterned larvae that I have ever 

 seen. The present species exhibits an unusual degree of depression for this 

 tribe of Tipulidae and in some respects gives strong indications of how the even 

 more accentuated conditions in the Cylindrotominae may have been brought 

 about. It seems probable that this larva belongs to the genus Tipula rather 

 than to any of the related genera. 



Tipuline No. 3. 



Locality: Tundra at Nome, Alaska, August, 1916 (F. Johansen). Three 

 larvae, two large and one smaller specimen. 



Two additional badly shrunken larvae bearing the following label: "Tipula 

 larvae C, about one-fourth inch below the plant-covering of the tundra behind 

 the winter house, Collinson point, Alaska, September 20, 1913." 



Length, 27-5-30 mm.; diameter, 4-5 mm. 



' Form plump and robust; colouration brown, the body clothed with an abun- 

 dant appressed dark pubescence, the dorsal ring of each segment that bears the 

 setae darkest in colour; each segment is divided by 4 or 5 pale transverse false 

 sutures so the abdomen appears multisegmented. The true limits of each seg- 

 ment are readily determined by the caudal row of setae. 



Chaetotaxy: Tergites (PI. V, fig. 64) with four long, powerful bristles in 

 ahgnment, the median pair closer to one another than either is to the lateral 

 seta; extending proximad from each seta is a narrow, semi-impressed line 



