THE GENUS ACRONYCTA AND ITS ALLIES. 



175 



which two emerged quite satisfactorily, ordinary full-sized 

 specimens, and the third is alive and well, and proposes to 

 face a fifth winter as a pupa. 



In this district it affects aspen as its proper food, but occurs 

 on other species of poplar. I have seen it, but very rarely on 

 sallow ; it does not range far north, at least on the west coast, 

 but I do not know its exact limits. 



Notes on Plate III. — The pupae here illustrated are the 

 most typical Cuspidice. They all have the two dorsal hooks, 

 and of the three ventral hooks on either side, all have the 

 two inner ; alni, strigosa and tridens have also the outer in typical 

 form ; psi has this outer one simply, or more usually duplicated 

 into two on either side. In megaccphala it is represented by a 

 lateral group or 6 or 7 hooks. Taking tridens for comparison, 

 then psi is extremely similar, strig&sa, though of the same 

 pattern, has the hooks very long and delicate, proportionally 

 (to the smaller pupa) about twice as long. Abii has the hooks 

 much the same, but more spread and more hooked, and has in 

 addition the remarkable special groove, with its fluted margin 

 and remarkable smooth escutcheon on the boss below. In 

 Glea there is a suggestion that such a structure might arise, 

 but I am not acquainted with any other pupa with this groove 

 fully developed. The drawings, which are well reproduced in 

 the plate, convey a very accurate impression of these struc- 

 tures, and are indeed most excellent and successful. Only in 

 megaccphala is the success at all modified. 



EXPLANATION OF PLATE III. 



Fig. 



Natural Size.— I. — Pupa 0^ Aci onycta {Cusp. 



Enlarged J la. „ „ 



8 diameters. ]_ lb. ,, „ 



Natural Size. — 2. „ „ 



f2a. ,, ,, 

 Enlarged , . 



8 diameters. \ ' " " 

 L2d. 



Natural Size. — 3- >> )) 



Enlarged I 3b" " " 

 Q diameters. 1 



Natural Size. — 4- ji n 



f4a. „ „ 



< 4b. „ „ 



L4'^- ,, 



Natural Size. — 5- n n 



Enlarged ' S'^- )j j! 



6 diameters. ) ^c. „ ,, 



Enlarged 

 9 diameters. 



mature. 



{To be continued.) 



