313! XOCTVID LARVAE— RIFLEY 71 



the present state of our knowledge of their phylogeny. They are probably 

 non-recapitulative but are evidently not to be explained by the mechanics 

 of growth, since exceptional instances occur. 



It was mentioned in the morphological part of this paper that the seta 

 of the proximal segment of the palpus presents a specialized condition with 

 reference to position in Lycophotia margaritosa, where it is located mesad 

 instead of laterad of the small terminal segment (Fig. 38), a very excep- 

 tional situation. The location of this seta is normal in the first instar 

 (Fig. 3i3i), the unusual position found in the later instars being the result 

 of its migration around the cephalic side of the distal segment. This process 

 is unquestionably a recapitulation. 



The postembryology of the spinneret of noctuid larvae is a highly com- 

 plicated and most interesting subject. Four distinct types of development 

 of this structure have been observed and most probably a more extensive 

 study will reveal the existence of a number of additional ones in the order. 

 In Type I the spinnerets of both first and last instars are subequal in length 

 and distinctly longer than in the intermediate stadia. The species of Phy- 

 tometra examined present this condition. Type II is represented by 

 Lycophotia margaritosa. The spinneret of the first instar of this species 

 (Fig. 34) is much longer than the palpi and fairly slender, the condition 

 most frequently found in the fully grown larvae thruout the family. In 

 the second stadium it is very much shorter and reveals slight projections 

 on both upper and lower distal margins (F.gs. 35, 36). The reduction m 

 length proceeds a little further in the third instar and the distal projections 

 become longer (Fig. 37). ^Moreover the lateral emarginations, which are 

 very rudimentary in the first two stadia, are fairly deep in this one, so that 

 the upper and lower lips, previously described, become evident. From this 

 stadium to the last there is no appreciable change in relative length, but 

 the projections gradually become elongated on both lips, forming a well 

 developed fringe, and the proximal fold and its sclerite decrease consider- 

 ably in relative width. The lower lip shows a tendency to become bilobed. 

 The decrease in the relative size of the sensoria has already been discussed. 

 Polia renigera exemplifies Type III. The spinneret of the first instar is 

 somewhat shorter than the palpus (Figs. 29, 30). In the following stadia a 

 gradual increase in its relative length occurs and the proximal fold becomes 

 markedly elongated on the cephalic aspect. The condition in the fully 

 grown larva is shown in Figures 31 and 32, where the spinning organ is 

 somewhat longer than the palpi and the extension of the proximal fold 

 reaches about half way to its distal end. The secondary chitinization of the 

 spinneret and of the proximal fold, like that between the sensoria of the 

 proximal sclerite, does not appear until the last instar. Type IV presents 

 very little change in the relative length of the spinneret in diSerent instars, 

 as may be seen by comparing Figures 40, 41, 43, and 44, representing the 



