based on the principle of Cephalization.—Insects. 19 
¢. Lrichopters:—The Trichopters, while permaturative like the 
Lepidopters, are semiaquatic, and he re inferior to both 
Lepidopters and Homopters. wings are pilose, are 
tion is evidence of superiority of rank among Insects in general. (See Agassiz on 
the Classification of Insects from Embryological data.) But as Lepidopters are on 
various ae : 
re) ms: ta ’ 
Condition; it is a degradation of — type, as much as when the digestive system 
; d Worms becomes atrophied with growth. 
Exceptions like these do not set aside the embryogenic law of grade: they only 
show that this law : 1 b 
cephalization, before it can be safely followed in determining the grade of s 
in embry 
vidual growth, ‘he 
‘latter principle, once recognized, more than reciprocates. 
