Notes in 1887 upon lepidopterous larve, dc. 559 
upon this ridge, and thus becomes even more con- 
spicuous. Posterior to the second tubercle, and on a 
rather lower level, are two minute white dots, one 
or both of which may perhaps represent the additional 
tubercle seen in Sphinx larve ; but more probably the 
posterior of the two strongly-marked bristles on the 
first tubercle represents the posterior of the two dorsal 
bristles which rise from separate tubercles in young 
Sphingide. The arrangement above described will be 
found to closely resemble that present upon the larva of 
Sphinx convolvuli in the first stage (see Plate XV., fig. 2), 
and other previously described Sphinx larve (S. ligustri, 
S. ocellatus, &c.). During the past summer I have had 
the opportunity of examining the newly-hatched larve of 
Sesia fuciformis, and the very remarkable furcate spines 
on the dorsal tubercles evidently represent and strongly 
suggest the double spines on the first tubercles of Aglia. 
I have described the tubercles of Aglia in some detail, 
because it is impossible to fully represent them in a 
drawing of the size represented in fig. 3. The single 
median spine which certainly represents the caudal 
horn of Sphingide, and which will in future be called by 
this name, takes the place of the two first tubercles on 
the 8th abdominal segment. The two branches into 
which the horn diverges at its extremity, probably repre- 
sent, as Wilhelm Muller suggests, the essentially double 
nature of the structure, which has arisen from the 
coalescence of two dorsal tubercles. The only apparent 
objection to this homology is the precisely similar struc- 
ture and appearance of the four thoracic spines, which 
at first sight seem to render it difficult to consider 
that each of these latter is morphologically equivalent 
to only one half of the caudal horn. It is, however, 
probable that they may represent the two dorsal 
tubercles on each side fused together in a longitudinal 
direction, just as the caudal horn represents a single 
pair which has coalesced in a transverse direction. The 
planes in which the bifurcation of the spines takes 
placé respectively, seems to support this interpretation. 
Furthermore, the two highest dorsal tubercles are 
represented by a double tubercle on each side of the 
2nd and 38rd thoracic segment in the young S. convolvult 
(and in many other larve: see, for instance, the figure 
of Huclidia mi, Plate XVII., fig. 8, x 24°5). 
