1890 .] 
539 
[Packard. 
double red and yellow dorsal lines between the head and the horn 
on the first abdominal segment is the same in the two species, but 
the space they occupy is wider in S. unicornis , while the corre- 
sponding dorsal lines of the first behind the horn and the second 
and third segments are firmer, less wavy than in S. unicornis. The 
horn of the first abdominal segment is higher and slenderer, not so 
thick at the base as in S. unicornis , while those on the eighth ab- 
dominal segment are much higher and more prominent. The four 
pairs of dorsal oblique lines of $. unicornis are less distinct in S. 
ipomece and more wavy, while the Y-shaped dorsal mark just be- 
hind them is less sharp and distinct with more red interlineations 
in S. ipomece. 
The first stage of S. unicornis (Fig. 1) differs but slightly from 
that of S. ipomece. 1 The head and body are of the same propor- 
Fig. 1. ScMzura unicornis stage I. Bridgham del. 
tions, the pro thoracic tubercles of nearly the same size, but those 
on the back of the meso- and metathoracic segments are larger 
than in S. unicornis. The tubercles on the abdominal segments 
are of nearly the same proportions, but slightly larger. 
The first, third and eighth abdominal segments are bright-red in 
unicornis as in ipomece , and the colors and markings in general 
scarcely different from those of ipomece. The anal legs are the 
same in size and position in the two species, but the tubercles are 
on the whole larger in ipomece. 
The hairs are clavate in unicornis and of the same proportionate 
length as in ipomece. 
It thus appears that no genuine specific differences exist between 
the freshly hatched larvae of S. ipomece and unicornis and most 
1 The great apparent difference between the figures of stage i of S. ipomece and S. 
unicornis, is due to the difference in their preservation, the body of S. unicornis having 
been much contracted by the alcohol. 
