PHYLOGENY OF THE NEMOCERA. 267 



(as in P. consobrina) are, like the modified hind tarsi, found in 

 both sexes. 



Among the Cyclorrhapha, as might be expected, we find the 

 characters of the legs extremely developed. Among the Syrphi- 

 dse, though there are many such simple forms as Chilosia, \ve find 

 progressive degrees leading to great complexity, as in Platycheirus 

 and Pyrophana. Such a form as Sphcerophoria scripta is an 

 intermediate one; the general type is simple, but the under 

 side of the middle femora of the male is studded with short 

 sharp hairs absent in the female. The four genera of the Cono- 

 pidae examined all show a greater specialization than Sphcero- 

 phoria. Gastropliilus equi has a long shaggy pubescence far 

 removed from the simple forms. Of the Muscidae alone a 

 chapter might be written on the variations of the pubescence and 

 bristles of the legs; and some flies, like Glossina, have structures 

 which appear to be characteristic. All these modifications are 

 those of strong bristles, though softer hairs are often present. 

 I can not call to mind instances, unless it be Calobata where the 

 pubescence is uniformly like that of Gynoplistia and the Panor- 

 pidae, soft and w T eak. 



ON CERTAIN GLANDS IN THE MOUTHS OF SOME MYRIOPODA 



AND DlPTERA. 



In the limb-like maxillae of Scutigera (a centipede with com- 

 pound eyes) there are organs of striking structure. In addition 

 to the poison glands, which may easily be mistaken for tendons 

 or overlooked, there are transparent chitinous bulbs communicat- 

 ing with apertures in the claws by ducts of moderate length. 

 These bulbs are studded with a number of short tubular processes 

 which show clearly when the edges of the organs are focused. 

 These are peculiar structures of characteristic appearance, and 

 are very unlikely to be confounded with other organs. I naturally 

 reached the conclusion that these were poison glands, as the bite 

 of the centipede, in addition to the punctures of the claws, is 

 known to be poisonous. With this idea I was surprised to find 

 in the maxillary palpi of Rh yphus fenestralis 9 a similar structure 

 which I have figured in the cited paper on mouth-parts, as sense 

 organs. These communicate with the air by fairly large openings 



