Xylota. 511 



front margin of the pupa lie the two bifid spines, which remain, when 

 the pieces for the opening have been detached ; the length of the pupa 

 is 7 — 8 mm. It will be seen that the larva of nemorum is more similar 

 to that of pigra as described and figured by Perris, than is the larva 

 of segnis. With regard to the description and figures by Perris I shall 

 draw attention to the faet that the way in which he describes and 

 figures the segments of the larva is erroneous; the place of the anus 

 shows that the last segment is long, and when we count twelve seg- 

 ments (the head taken as one segment) we also see that this is so ; when 

 the head, the three thoracai segments and the six proleg-bearing seg- 

 ments, in all ten, are counted, we have still a small eleventh segment 

 and then the long twelfth segment with the anus at its front end. 

 That Perris has made some error is also seen from the faet that 

 while he says there are eleven segments without the head, he says 

 later on that there are nine abdominal segments, which would give 

 twelve segments without the head. — Perris mentions that the opening 

 of the puparium is caused by a frontal bladder; this is, of course, 

 erroneous. 



The species of Xylota are beautiful and characteristic flies, and 

 the larger species are rather strong. They occur in woods, generally 

 on humid piaces or near water, and they are here seen running on 

 large leaves in low herbage, f. inst. on leaves of Tussilago and Petasites; 

 some species are especially seen on tree-stubs and stems or on piles 

 of wood; they are shy but when disturbed they usually use their legs 

 running rapidly away and often seeking the underside of the leaves, 

 but they also fly well, though generally not for long distances. 



Of the genus about 22 species are recorded from the palæarctic 

 region, 8 have been found in Denmark, 



Table of Species. 



1 . Abdomen red on the middle part 2. 



— Abdomen black, or with pairs of yellow or glaucous spots. ... 5. 



2. Legs partly yellow 3. 



— Legs all black 4. lenta. 



3. Hind femora with equal and rather strong spines below in 

 nearly the whole length ; hind trochanters in the male with 



a large spine 1 . segnis. 



— Hind femora very short-spinulose below, only with some- 

 what small spines towards the apex; hind trochanters in 



the male with a short spur or process 4. 



4. Anterior tibiæ with blacklsh rings, hind tibiæ with the apical 



two thirds black 2, tarda. 



— Tibiæ yellow 3. ignava. 



