12 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



Noctnidae: In this family the proboscis and its musculature are 

 very well developed. The cranial proboscis extensor here reaches a 

 remarkable size and importance, in comparison with the tentorial pro- 

 boscis muscles. This is of interest in view of the fact that the cranial 

 proboscis extensor is the muscle most frequently absent in cases where 

 there is not a full complement of proboscis muscles. The proboscis 

 musculature of a large moth, Catocala niihilis, is shown in figure 6 A 

 and is in general typical of the family. 



Arctiidae: All examined members of this family have degenerate 

 feeding mechanisms. Figure 6 C shows a section through the head of 

 a typical species, Apantesis virgo. Both A. virgo and A. vittata have 



-Ant-Nv 



BVGng- 



antmc) 



Pfb- 



Soe Gng- 



B 



atp sip Ptp 



Fig. 5. — Proboscis extensor musculature and the sucking pump. 



A, right half of head, mesal view, of Hacmatopis grataria, as exposed by 

 median sagittal cut. B, same of Ennomos stibsignarins. 



all three pairs of proboscis extensors. The posterior tentorial probos- 

 cis extensor originates well back on the anterior arm of the tentorium. 

 Estigmene acraca and UtetJieisa hella show about the same conditions. 



The members of the genus Haploa exhibit the strongest proboscis 

 musculature seen in this family, and there can be but little doubt that 

 the proboscis is functional. The members of the genus Diacrisia, on 

 the other hand, have the most degenerate feeding mechanisms seen 

 in this family. In D. virginica the anterior tentorial proboscis exten- 

 sor has been lost and the posterior muscle is very weak. The cranial 

 proboscis extensor is still evident. 



In Isia isahella all three pairs of proboscis muscles are present and 

 apparently functional. The anterior tentorial proboscis extensor, how- 

 ever, has migrated to the antennal ridge, above the anterior arm. 



Saturnoidea: The degeneracy of the feeding mechanism in the 

 giant silk moths is so complete that there are few traces left of the 



