MAY FLIES AND MIDGES OF NEW YORK ' 265 



Imago. Resembles Crjcotopus and Gamptocladius. 

 The fore metatarsus is shorter than the tibia; the legs are not 

 black and white annulate, but nearly uniform in color, either 

 dark or light, in the latter case at most with only dark articula- 

 tions. Wings bare, R^ enters the costa beyond the mid length of 

 the wing; R^^. straight or only slightly bent, reaching the end 

 of the cO'Sta; crossvein at or even before the mid-length of the 

 wing; the forking of the cubitus usually noticeably distad of the 

 crossvein; the posterior branch straight or gently curved. Geni- 

 talia of the type shown on pl.33, fig.l, thus resembling C r i c o t o- 

 pus (fig.2). The species usually small, though occasionally of 

 moderate size. In other respects like C h i r o n o m u s . It will 

 be noted that it does not differ structurally from Oricotopus, 

 differing only in color characters. 



KEY TO SPECIES OF ORTHOOLADIUS 



Larvae 

 a Mandible slender with sharp apex ; antennae slender ; margin of labium 



irregular, pl.24, fig.l2 '. 5. f 1 a v u s n. sp. 



aa Mandible rather stout ; margin of labium with regular teeth 



h First laterals of the labium notched on the outer margin; mandible 



with lateral surface wrinkled 15. f u g a x n. sp. 



&& First laterals with rounded margins 



c Labium on the lower surface with two converging folds, pl.25, fig.l4 



7. sordidellus 

 cc Labium without these folds, pl.24, fig.21 8. nivoriundus 



Pupae 

 a Posterior margin of each abdominal segment with a row of long stout 



setae, pl.24, figs. 15 and 16 5. f 1 a v u s n. sp. 



aa The segments without these setae 



J) Dorsal surface of each segment nearly uniformly covered with minute 

 spines and four pairs of setae; respiratory organ with enlarged 



apical end, pl.24, figs. 22, 23, 24 8. nivoriundus 



&& Dorsal surface with several transverse patches of minute spines 



c The patch covering the center of the disk of each segment largest, 



pl.25, figs. 7 and 11 15. f u g a x n. sp. 



cc The middle band consists of two irregular rows of short stout spines 



7. sordidellus 

 Imagines 



a Yellowish species. (The females, and the species with brown abdomens, 



should be sought for in the next section also.) 



& Large species 6 mm. in length ; yellow ; thorax with threo dark yellow 



or brown stripes ; abdomen with two brown spots on each segment ; 



male 1. par 



