THE GENUS ACRONYCTA AND ITS ALLIES. 
129 
in addition to the olive tubercles they have a dark central line 
(transverse) or shade, on the loth the anterior tubercles are 
dark, but the posterior nearly of the yellow of the ground 
colour; the nth, 13th and 14th are uniformly pale (these pale 
portions are on the pale area of 4th skin), the 12th has the 
tubercles very dark, thus resembling the 2nd. 
The paleness of the pale segments is increased by the space 
on the loth and nth, between the lozenges, being nearly as 
pale as the lozenges themselves, and by an isthmus passing 
from the nth to the 12th. There are also, on the forward 
segments, traces of a yellowish dorsal line, and also of a sub- 
dorsal line at the margin of the lozenges. The dark portion of 
the larva has not the velvety metallic sheen of the ordinary 
full-grown larva, and it is broadly marked by the pale lateral 
band (on level of sub-spiracular tubercles) that the larva has 
temporarily just after moulting into the last skin. This line 
fades slowly upwards, it tends to invade 3 and 4 in the inci- 
sions of those segments, narrows rather on 8, 9 and 10 ; on 1 1 
it throws a curious branch upwards and forwards, and is con- 
tinuous with the lozenge on 13 (suggestive of juvenile tridens). 
The circum-spiracular tubercles are black (with short hairs), 
and surrounded with narrow pale rings (like various other 
species) on 7, 8, g and to. The marginal tubercle has two 
hairs. The sub-spiracular tends to be olive coloured, as do the 
others on the pale segments. There is a faint pre-spiracular 
tubercle. The nth segment is markedly lower than the others, 
whilst the 12th is distinctly humped. The hairs are rather 
more clubbed than is usual in 4th skin, less than in the last ; 
length of clubbed hairs on 8th segment 2f mm. This larva 
died when in its last skin, owing to ill-usage. 
The only variation noted in larvae in their last skin was a 
band connecting the lozenges of 12 and 13, making one dumb- 
bell-shaped mark. There is, however, considerable difference 
in the intensity of the yellow, from pale lemon to orange. 
No detailed remarks I could make would add to the evidence, 
these two vars. of larva in extra (5th) skin afford, that alni was 
once a 5-moulter, like the other species of the genus, and that 
intermediate forms between the present 4th and 5th skin 
plumages at one time existed, some features of which are pre- 
served for us by these atavistic variations, and it is also 
interesting that, in the latter form, at any rate, some features of 
other species of the genus are presented, which are quite absent 
in normal alni. 
c 
