THE SPHINGO-MICROPTERYGIDES. 129 



wander far to lay their eggs, yet they do wander, and the females of 

 Endromis versicolor, Saturnia pavonia, Eutricha quercifolia, Lasiocampa 

 qiiercus, Cosmotriche potatoria, etc., do not lay all their eggs at one 

 time, nor in one place. Most of these pair where they emerge, lay a 

 batch of eggs near this spot, and then fly a short distance (and pro- 

 bably pair again) before laying another batch. Still, there is, owing 

 to the sluggish habits of the female, a tendency to segregation in all 

 these species. 



With regard to the relative age of the various superfamilies 

 belonging to this stirps, Packard says that he has always regarded the 

 Bombycids (the superfamily of silkworm moths) as a very ancient one, 

 which has lost many forms by geological extinction. This accounts 

 for the many gaps between the genera. Both the larva? and imagines 

 differ structurally inter se, much more than do those of the Geometrid 

 and Noctuid moths, and the number of species is less. 



The completeness of the two latter superfamilies suggests that their 

 species have been, to a great extent, developed since, or contempo- 

 raneously with, the early Tertiary period. On the other hand, Packard 

 supposes that the Bombycids originated previous to Tertiary, and 

 probably in Cretaceous, times, and he suggests that the plasticity of the 

 Bombycid larval forms, especially in the more generalised families, is 

 due to the great changes in their environment during the Cretaceous 

 and Tertiary periods. In like manner, Packard says, the great gaps in 

 the genera of our existing Bombycids are probably due to geological 

 extinction, and also to the great plasticity or marked difference in the 

 larva?, as compared with the homogeneousness of the imagines, these 

 being due to the widespread changes in the environment which took place 

 during the late Mesozoic and Tertiary periods, and which reacted on 

 the insects in their early rather than their later stages. Packard 

 further says : " Were fossil Bombycids ever to be found in Europe, we 

 should expect to discover among them representatives of the Cochlio- 

 podidae, of the Attacine families (Saturniidae and Ceratocampidae), now 

 characteristic of North and South America, or of the tropical regions 

 of Asia, and perhaps of Africa." He bases this view on the theory that 

 these groups have, to a great extent, become extinct in Europe, but 

 still remain characteristic of the American fauna. He says : " Where 

 a family or subfamily is equally developed both in the Old and New 

 Worlds, we are inclined to suppose that it has been a recently evolved 

 group. It is well known that America has lagged behind Europe, 

 geologically speaking, although America is the older continent as such ; 

 the process of specialisation, and then of extinction, has gone on more 

 rapidly in the Old World, or at least the western portion of it " (Bomby- 

 cine Moths of America, p. 32). 



Superfamily I : MICROPTERYGIDES. 

 In Hiibner's Verzeichniss, etc. (1826), the genus Micropterix (Microp- 

 teryx) was founded to receive three species, mucidella, Hb., podevinella, 

 Hb. ( = aruncella, Scop.), and pusilella, Hb. ( = calthella, Linn.) The 

 first species being an Elachista, it leaves aruncella and calthella as repre- 

 sentatives of Micropteryx, Hb. In 1839, Curtis separated (Brit. Ent., 

 xvi.) the British Micropterygid and Eriocraniid species from Lampronia 



* This term is used by Packard to include the Saturniids and Lasiocnmpids, 

 as well as the Bombycids proper, 



