242 Lilian J. Gould's experiments 



eyes, of which the pupil was yellowish red, viz., the 

 spiracle itself ; the iris green, boldly outlined with red 

 (PI. XL, fig. 12). 



Aug. 22nd. — The fourth ecdysis occurred. Both rows 

 of spots slightly increased in size, lengthening vertically 

 so as almost to connect stripe with stripe, but not in- 

 creasing horizontally. The appearance was not in the 

 least border-like. 



Sept. 5th. — The spiracular row of spots was now 

 eleven, another having appeared ; there was a spot on 

 each of thoracic segments two and three, the one on 

 thoracic segment three being a mere trace. (On these 

 segments there were no spots in S. tilia). The spots 

 were still more eye-like, being more broadly margined 

 with red. The upper row of spots now numbered eleven 

 also, the extra spot occurring on the last segment, verti- 

 cally above the last of the lower row. The last spot but 

 one occupied five rings (two in the penultinate segment, 

 and three in the last) ; this was the only one which in- 

 vaded another segment. The first, second, third, fourth, 

 and fifth spots occupied four rings, and the eleventh, 

 first, second, third, and fourth only three rings. But the 

 tenth, eighth, seventh, and sixth were the largest, owing 

 to vertical extension, and these slightly suffused the 

 stripes. Both sides corresponded. The head was 

 suffused with red. The thoracic legs were red, and there 

 was a red spot on each of the claspers. The ground 

 colour of the caudal horn was yellow, the base was 

 blackish above and reddish beneath, and a red line ran 

 up from in front of the seventh stripe to the base, 

 connecting it with the tenth spot. This line was the 

 only attempt at extension borderwise, for the widening 

 on August 22nd was accompanied by great vertical 

 extension, which quite prevented a border-like appear- 

 ance. The larva ceased feeding on Sept. 8th, and pupated 

 during the night of Sept. 14tli. The spots in S. popidi 

 were unlike those in S. tilice in general effect, being 

 rounder, bolder, and not in the least linear, and I noticed, 

 as had been previously done by other observers (notably 

 Mr. Peter Cameron, as stated by Prof. Meldola in his 

 notes to Prof. Weismann's ' Essay on the Markings of 

 Caterpillars'), that they were strongly protective, from 

 their resemblance to the dark spots or blotches commonly 

 seen on the leaves of the poplar. Viewed from under- 



