14 NYSSIA. LAPPONARTA. 
Before the fourth moult, thirty-two days old, it 
measures nine-tenths of an inch. As in the previous 
stage it is cylindrical, and of uniform thickness 
throughout; the ground colour is pale primrose-yellow; 
the longitudinal bands, which are outlined with fine 
black lines composed of numerous black specks and 
streaks, have the interspace of a leaden-drab colour, 
these bands being divided by primrose-yellow lines, 
thus forming longitudinal rows of alternating stripes ; 
the leaden-drab stripes are medio-dorsal, subdorsal, . 
superspiracular, and spiracular; on the latter band 
are situated the spiracles, which are small and intensely 
black; each is placed on a squarish dull deep black 
spot, forming a conspicuous row of spots; each is 
bordered on the lateral and posterior sides with bright 
lemon-yellow, the yellow being again relieved laterally 
by a black streak ; on the posterior half of each seg- 
ment uniting the medio- and subdorsal bands is a short 
transverse lemon-yellow bar united to a black spot in 
the subdorsal band. The remaining details are in 
every way similar to the previous stage. It rests ina 
straight position upon the stems of birch, frequently 
straight along the stem, but sometimes only with its 
claspers grasping it, and the head a short distance 
away, but always with a silken thread from its mouth 
to the stem. ‘The fourth and last moult took place on 
the 18th June. 
After the fourth moult, forty-two days old and 
fully grown, it measures an inch and a half in length. 
In every detail the preceding description agrees 
precisely with this stage, excepting that the yellow 
markings are now rather deeper, of a gamboge-yellow, 
and the ground colour of the dorsal surface is also 
rather deeper, and of course the size increased when 
fully grown. ‘The ground colour varies in different 
specimens ; of the four larvae in my possession three 
having the yellow of different depths, and the fourth 
of a decided lilac-drab hue ; this, with the black 
markings, assumed quite a deep drab-brown, closely 
