PTEROPHORUS MICRODACTYLUS. 371 



quantity must occasionally have fallen out of the 

 holes ; the mines always appeared lightly filled up 

 from within, just level with the surface of the stem, 

 and so the orifices not contrasting much in colour, 

 were not very conspicuous from being no more than 

 one-sixteenth of an inch in diameter. 



The youngest larva examined I found to be just 

 one-eighth of an inch long, and possessed of all the 

 details of form, colour, and other characteristics that 

 so well distinguish this species of Pterophorus from 

 any I have as yet seen, inasmuch as it is furnished 

 with rough points or hooks, in many respects much 

 like those we know so well on the pupse of Cossus and 

 of Hepiahis ; doubtless these are both for support and 

 progression within the very tough stem where it 

 resideSo 



The full-grown larva is one quarter of an inch in 

 length, plump in proportion, in general figure some- 

 what cylindrical, but tapering forwards to the head, 

 which is smaller than the second segment, the last 

 three segments also tapering to the anal tip ; the 

 anterior legs are but little developed, while the ventral 

 and anal legs are so exceedingly small as to be with 

 difficulty detected even with a lens ; the segments are 

 well defined ; the first third of each, after the thoracic 

 segments, is clean cut backwards with an upward 

 slope, and the summit of this slope is crested with a 

 row of minute rough points, or blunt hooks, extending 

 unbroken across the back, rather near towards the 

 spiracular region ; on the middle portion of the 

 remainder of each of these segments is a broadish 

 oblong transverse band of the rough points dorsally 

 divided by a naked, or nearly naked, interval of 

 smooth skin ; similar points occur also across the 

 thoracic segments, but in a narrower shape, and on 

 the second they fill up the usual form of plate there ; 

 those on the twelfth segment, and the front of the 

 thirteenth, are very much coarser, and closely aggre- 

 gated. 



