98 NEW YORK STATE MUSEUM 



mandibles are the most conspicuous, slender at the tip and 

 simple, but enlarged basally (pi. 18, flg.4). The labrum is rounded 

 and provided with one or two pairs of papillae, which may be 

 larger than the antennae and of similar construction (pl.18, 

 fig.Ib). The maxillae (tig.2j/(./) are fleshy, lobed, and each pro- 

 vided with a large two-jointed palpus (p). The labium is quite 

 small and inconspicuous, and differs from the corresponding part 

 in Chirouomus in having a soft and rounded edge, but 

 upon its inner surface forming the floor of the mouth cavity it 

 is heavih' chitinized and formed into one or more cephalad pro- 

 jecting teeth (pl.18, fig.2^). The thorax and abdomen are wholly 

 without prolegs; usually with but few or no setae excepting at 

 the caudal end where there are about eight long setae and a few 

 short ones. Projecting from the rectum, when not retracted, 

 may be seen the delicate white blood gills. 



The pupa is brow^nish, somewhat tapering, with an ovate 

 thorax. It floats nearly motionless at the surface of the water, 

 or is attached to plants a little above the surface but still 

 W'ithin the water film. The respiratory trumpets are slender, 

 and more or less cylindrical with the aperture slightly enlarged 

 (pi. IS, figs.9 and lOt) . The abdominal segments are provided with 

 spines, setae and tubercles. The anal fin ends in two pointed 

 lobes (pi. IS, fig.ll). Professor Mik, on page 183 in Vol. 7 of the 

 Wiener Ent. Zeit., described a species of Oeratopogon 

 with hairy wings, but having a footless larva. This form occu- 

 pies a place between the above two groups; and its habitat, the 

 very moist or Avet. ulcerous parts of the stems of A e s c u 1 u s 

 hippocastanum, also suggests an intermediate form. 

 This species differs from all known members of both groups in 

 possessing instead of either setae or prolegs a retractile disk, 

 on the periphery of which are arranged five pairs of curved 

 spines. It agrees with the second group in having no prolegs, 

 and with the first in having a mandible with a three-toothed 

 margin. 



The pupa has cylindrical, elongate respiratory trumpets; the 

 abdomen is provided with spiny tubercles, and the caudal end 

 has a crown of tubercles. The adult would be classified with Kief- 

 fer's aenus Culicoides, 



