rune, 1896.] GROTE : On DISTRIBUTION AND MlMICRY OF APATELA. 83 
barriers. There is also the dependency upon food plants and geog- 
nostical conditions to be considered. At any rate, the central Cali¬ 
fornia fauna must be studied from the point of view that it is isolated 
upon a comparatively narrow strip of land as compared with the fauna 
?ast of the main range. And this view must be taken of the fauna of 
the West Coast, both in North and South America, wedged in as it is 
between the sea and the mountainous backbone of the New World. 
The very near relation between the moths of psi, tridens and occi¬ 
dentalism while the larvse are so strikingly different, recalls the case of 
Datana and Phalera, though here the larval characters are decidedly 
stronger and even structural. We may assume that here the tendency 
to split into distinct larval forms was early developed, and that it ex¬ 
emplifies the fact that specific characters in Apatela are best, perhaps 
first, expressed in the younger stages. The two European species seem 
altogether nearer, and lead to the impression that they have a more im¬ 
mediate connection, while the American probably left the common an¬ 
cestor at the close of the Tertiary. 
In 1894, Dr. Harrison G. Dyar discussed the appearance of the 
larvae of Apatela , and his remarks are in part applicable to the Euro¬ 
pean forms. The diversity is mainly ascribed to a “mimicry of all 
sorts of objects, from that of resemblance to the foliage ( grisea , tn'fona), 
to warning colors ( oblinitd ) and mimicry of special objects, such as 
spider’s nest ( vulpina ) or of some other specially defended larva (rad- 
cliffei mimics Datana , or luteicoma , which probably mimics Orgyia ).” 
Previously, in 1893, Dr. Chapman had discussed the mimicry of the 
larvae as follows: “The protection which the full grown larvae have 
from their enemies, owing to their special form and coloring, is a mat¬ 
ter that in its details, has very largely eluded me ; I have, in fact, seen 
very few Cuspidia in the wild state. Psi and tridens are usually con¬ 
spicuous ; strigosa no doubt closely assimilates to a hawthorn leaf with 
a bit of brown dead leaf or twig. My observations on leporina were 
made and repeated a good many times on the green white-haired form 
occurring on alder; this larva sits somewhat curled round, near the 
middle of the underside of a leaf. Looking down from above it is ab¬ 
solutely hidden, looking up from beneath it ought to be very evident, 
but this is far from being the case. I have several times missed a larva 
till I have looked three or four times, and have also fancied I saw a 
larva when none was there. In looking up from below through the 
foliage of an alder tree, most of the lower leaves are in the shade of the 
upper ones, but here and there a gleam of light falls through on to a 
