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12

Smithsonian contribution to Knowledge

Vol II. Art 6. "The Classification Insects from Embryological Data by Prof. L. Agassiz.

p. 20 insists that the 4 great classes of animals are not comparable

p 21 his principle "that in the growth of animals their successive changes are progressive, are steps forward." Disputes that Lernaea are retrograde because male Proteolepas. He applies his principle thus, he takes metamorphosis of insects as his type from apparently being most perfect, & then compares all articulata with the stages & thus ranks them. This wd be correct if Crustacea had proceeded from insects, or the reverse, but not applicable if both classes have

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Balanus	Larva of do
rudimentary eyes.	well developed, capable of movement
Acoustic sack	acoustic sack
olfactory organ	none
nervous system probably more condensed}
protected by complicated shell – opening & shutting}	protected by simple shell – opening & shutting}
six prehensile arms, with [illeg] different movements	six natatory legs
abdomen none but movable penis	abdomen natatory
fixed	locomotive
no antennae	complicated antenna prehensile & probably sensitive.
If we look at intellectual Lem must be highest.	as highest

 

from a common centre, which must have been the parent of the minute hexapod larva of Daphnia & of maggots - In one class as crustacea the embryological principle is applicable, because we may believe, only as probable, that the higher ones have descended from the lower ones, or forms allied to them.

(All this might be introduced, when I discuss practical bearing of Embryological characters)

p 25 admits ( [illeg] M. Edwards) that in classifying th highest articulate is that, in which. "all its peculiarities is gradually wrought out more & more fully & in its highest class recedes most from all other types".

p. 27 speaks of respiratory organs in Spiders being "lung-like sacs" & not true Tracheæ.

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Agassiz seems entirely to overlook special adaptation in larvæ.