Notes in 1887 upon lepidopterous larve, de. 571 
There are six spines on the 9th abdominal as on the 
segments anterior to the 8th. Minute rudiments of some 
of the spines are present on the 1st thoracic segment. 
All the spines are very uniformly developed, those in the 
dorsal rows being rather larger than the others, especially 
anteriorly. There is a much smaller spine beneath the 
inferior long spine on each segment. 
The presence of a distinct forked caudal horn, with a 
complete, uniformly developed, spinous investment is 
most interesting and suggestive. 
The larve here alluded to, and many more, make a 
very perfect transition from the condition found in 
Aglia tau, to that in which the spinous covering is 
uniformly distributed and uniformly developed. In 
Aglia and many of species of Ceratocampa, concentration 
and specialisation has led to extreme developments at 
either end of the larva, and diminution elsewhere. It 
seems to me that Sphinx has gone further in the same 
direction. The uniform spinous covering, certainly 
present in a rudimentary form in the youngest Sphinx 
larve, has become reduced to a far greater extent than 
in Aglia, and many species of Ceratocampa, so that at 
last only the caudal horn remains. ‘Tendencies in the 
same direction are seen in Aglia and Rhescynthis, which 
lose all the spines in the last stage. Other methods of 
protection are developed—terrifying marks, protective 
resemblances leading to concealment, &c.,—and the 
older mode of defence is abandoned, the caudal horn of 
Sphingide remaining as a remnant of the former condi- 
tion. 
If this be true, we should expect to find traces of the 
thoracic spines in certain Sphingide: we should expect 
that a remnant of the ancestral condition would be 
retained in some species. This appears to be the case 
with the North American genus Ceratomia, which is 
placed next to Smerinthus. The larva of C. quadricornis 
is described by T. W. Harris (‘‘Catalogue of North 
American Sphingide,” ‘The American Journal of Science 
and Arts,’ vol. 36, 1889, p. 282) as possessing a pair of 
short denticulated horns on the 2nd and 8rd thoracic 
segments, and a long bluish caudal horn. Traces of 
the other less-developed spines of Ceratocampa are 
also probably present, for he describes “‘two parallel 
series of little teeth on the first four segments,” and 
TRANS. ENT. SOC. LOND. 1888.—PART IV. (DEC.) 2Q 
