1847.] Winter Insects r^ Eastern JS'^cw York. 279 



On warm days in tlie latter half of winter this species may be 

 observed crawling with hurried steps upon the snow. It becomes 

 most numerous about the time the snow finally disappears, and is 

 then often seen on shrubs, fences, and buildings, and not unfrequent- 

 ly fmds its way into our houses. It is extremely common, occur- 

 ring most abundantly in the vicinity of streams of water, in M'hich 

 element the previous stages of its existence are passed. When 

 first excluded Irora its pupa state, it is of a pale yellowish color, 

 but gradually changes to black, this change commencing upon 

 the thorax. Copulation occurs immediately after the female 

 comes from the pupa state. 



4. Nemoura NIVALIS. The Large '■^ Snoic-JIi/." The "Shud-Jlj/.'^ 



Black; wings griseous, faintly banded, double the length of the 

 abdomen. 



Length, males somewhat under, females over half an inch; 

 wings expand about an inch. 



Head covered with minute whitish hairs, which are longer 

 and more obvious beneath the bases of the antennse and around 

 the mouth. Vertex with an obtusely impressed transverse line 

 immediately back of the two posterior stemmata, and a longitu- 

 dinal medial one, reaching from the former to the neck. Anten- 

 nas black, clothed with very short minute hairs, slender, setaceous, 

 as long as to the tips of the wings in the males and somewhat 

 shortev in the females, composed of about sixty joints; basal joint 

 short-cylindrical, its diameter doubh that of the third and follow- 

 ing joints; second joint intermediate between the fii'st and third 

 in diameter, its length and breadth about equal; the remaining 

 joints obconic, gra(kially diminishing in diameter and increasing 

 in length toward the tijis. Palpi clothed with very short, mi- 

 nute hairs, black; basal joints of the maxillaries lurid and slight- 

 ly diaphanous, penultimate joint rather the shortest and obconic, 

 the joint preceding it longest and obconic, the terminal joint oval, 

 and scarcely as thick as the others. Prothorax square, in the 

 females scarcely broader than it is long, somewhat narrower ante- 

 riorly, posterior angles rounded, all the margins slightly and ob- 

 tusely elevated, the posterior one more obviously so, often with a 

 dull fulvous spot at the base, or with this color spi-ead over the 

 posterior part of the raised margin, and more rarely a similar 

 spot at the middle of the apex; disk sometimes showing an im- 

 pressed transverse line, and a longitudinal dorsal stria. Expos- 

 ed portion of the mesothorax much elevated above the plane of 

 the prothorax, forming a transverse I'idge between the bases of 

 the ^Yings; clothed with short hairs; often with traces of dull ful- 

 vous around the wing-sockets; the portion of the mesothorax and 

 metathorax covered by the wings smooth and shining. Abdomen 



