MAY FLIES AND MIDGES OF NEW YORK 119 



abdomen in both sexes number eight. Length of the male about 

 4 mm.; of the female 4.5 mm. 



The larva. The larva of Psamathiomy i a i linear, 

 vermiform, and of a yellow color. The apparent number of seg- 

 ments of the body, including the head, is twelve, one for the 

 head, three for the thorax, and eight for the abdomen. The 

 thoracic segments are shorter than the following; the apical one, 

 into which the head is retractile, being the smallest. The 

 thoracic anterior inferior angles of the somites carry incon- 

 spicuous minute bristly tubercles, while the abdominal seg- 

 ments, with the exception of the first and of the anal segment, 

 are supplied in the same place with prominent rounded eleva- 

 tions or cushions which infringe on the anterior edge of the pre- 

 ceding segment. These appendages carry nine to ten parallel 

 rows of very minute dark colored teeth, giving them the resem- 

 blance to microscopic currycombs. In front of each row of these 

 teeth and standing at some distance one much stouter spine is 

 visible. The anal segment terminates in five conical and some- 

 what incurved fleshy appendages, one of which is ventral and 

 much larger and broader than the others. This appendage 

 carries near its apex a large bunch of short-curved bristles, 

 while those opposed to it bear several tufts of similar bristles, 

 and the intermediate appendages are quite glabrous. The' total 

 length of this larva is 5.10 mm. The length of the anal segment, 

 including its appendages, is .66 mm., that of the three thoracic 

 segments .66 mm., while the middle segments of the abdomen 

 measure .45 mm. in length by .90 mm. in width. The chitinous 

 mandibles are distinctly visible; they appear, as far as can be 

 made out, to be widely three-lobed or toothed, and to be in com- 

 munication with two long internal chitinous rods, with slightly 

 swollen heads, which terminate as far back as the last thoracic 

 segment. 



Pupa of the male. The pupa case, after the imago has escaped 

 through a dorsal slit in the mesonotum, shows distinctly the 

 three sternal divisions of the thorax, as well as the various seg- 

 ments of the abdomen. These are eight in number, unless the 

 anal terminal process is considered as a segment, in which case 

 the abdomen has nine segments. The sheaths of the legs are 

 quite free, bag-shaped, distinctly jointed, rounded at the ends. 



