AQUATIC INSECTS IN NEW YORK STATE 373 
horny with two brushes of hair above, between which is a very 
small ligula, covered with a small brush of hairs. Fans, com- 
posed of stout stem, bearing about 46 scythe-shaped rays, lined 
on the inside by very minute, equidistant, erect hairs of equal 
length. Thoracic proleg, faintly four jointed, subconical, retractile 
(introversible), very thin and transparent, crowned with about 
20 rows of short, starp hooks, apparently arranged in a circular 
manner; the hooks, of which 10 are in each row, seem to be moy- 
able to a certain extent, and are fastened or hinged to small 
chitinous rods in the epidermis. Tip of abdomen formed by a 
subcylindric body crowned with rows of hooks. Breathing 
organs below these hooks and on the upper side of abdomen; 
they consist of three short, cylindric, soft and retractile tenta- 
cles, which connect with large internal tracheae. In full grown 
larvae a spot more or less dark is seen on each side of thoracic 
joint; it is produced by the formation of the coiled breathing 
tubes of the future pupa. 
Pupa. General color when fresh, honey-yellow; prothoracic 
filaments brown, and the abdomen dorsally also tinged with 
brown, except a mediodorsal space. All the members have also 
a fine brown marginal line; prothoracic filaments consisting of 
Six main rays, issuing from the basal prominence and subdivided 
two or three times, so that-in most cases as many as 48 terminal 
filaments can be counted. Abdominal joints three, four, and 
five, each with eight well separated, dark brown and anteriorly 
recurved hooks. The four on each side separated by a medio- 
dorsal space; those on joint 3 less conspicuous than those on 
joints 4 and 5; joint 6 without armature; joints 7, 8 and 9, and 
also subjoint less distinctly armed near anterior margin with a 
continuous dorsal row of very minute posteriorly recurved 
_ points; ventrally joints 6, 7, and 8 have each four very minute 
anteriorly recurved hooks. 
Cocoon. Average length 3.5mm. Not completely made and 
not entirely covering the pupa, but tightly surrounding its larger 
portion. Shape very irregular, with no distinct rim at the 
upper edge, which is more or less ragged. The threads compos- 
ing it are very coarse, and the meshes rather open and ordinarily 
filled with mud. Not always fastened separately to objects, but 
frequently crowded together without forming, however, such 
corallike aggregations as in some of the northern species. 
That part which Riley called the labium in the above descrip- 
tion, appears to be a combination of labium proper and the 
hypopharynx. Often in dissection these two parts stick 
together and appear as one, but with a little care the hypo- 
