172 Mr. A. S. Packard on Aglia tau. 



EXPLANATION OF THE PLATES. 

 Plate X. 



Fig. 1. Psathyrocaris fragilis, 5, from the leftside. Nat. size. Both 

 the legs of the second pair are figured, to show their inequality. 



Fig. 2. Rostrum of the same. Enlarged. 



Fig. 3. The caudal swimmeret of another specimen, from above. X 3. 



Fig, 4. A leg of the fourth pair of another specimen. X 4. 



Fig. 5. An abdominal appendage of the second pair of another specimen. 

 X5. 



Plate XI. 



Fig. 1. Psathyrocaris fi-agilis. Mandible. X 9. 



Fig. 2. First maxilla. X 9. 



Fig. 3. Second maxilla. X 9. 



Fig. 4. First maxUlipede. X 9. 



Fig. 5. Second maxillipede. X 9. 



Fig. 6. Third maxillipede. X 4-5. 



[To be continued.] 



XXIII. — Aglia tau, a connecting-link between the Cerato- 

 campidge and Raturniidaj, and the Type of a new Subfamily^ 

 Agliin^e. By Alpheus S. Packaed. 



In this European Bombycine moth we have a most interesting 

 form surviving side by side with Saturnia, which seems to 

 be the most generalized form of its family. Aglia appears 

 to be a Ceratocampid in its earlier larval stages, the cater- 

 pillar in its final stage, however, and the moth being closely 

 related to the Saturnians. It seems quite reasonable to 

 suppose that the Saturnians have directly descended from a 

 form like Aglia, and we could scarcely expect a clearer 

 demonstration of the origin of one family from another by 

 direct genetic descent. 



The transformations of this form, originally figured in 

 Luponchel and Guen^e's ' Iconographie ' * (torn, ii.), have 

 been more fully elaborated by ]\lr. Poulton •\. 



Having received, through the kindness of Dr. Heylaerts, a 

 young larva of Aglia tau in its third stage, I have been able 



* Guen^e states that, after attaining its full size, " eUe se retire a la 

 surface de la terre, entre des mousses et des d(?bris de T^g(5taux qu'elle 

 attache avec de la soie, et elle s'y change en uue chrysalide grosse, courte, 

 d'un brun fence saupoudre de grisatre, et dont I'anus est termine par un 

 faisceau de pointes recourb^es." 



t Trans. Eut. Soc. Loudon, 1888, pp. 555-668, pl. xvii. figs. 1-7. 



