1897] FOSSIL APODIDAE 401 
We have then, it seems to me, a simple and natural interpreta- 
tion of the shape of the shield of Protocaris without assuming any 
other distortion than that due to flattening. Had there been any 
horizontal distortion, it would, one would expect, be more apparent 
in the abdomen than in the shield. I am therefore disposed to look 
upon Protocaris as an Apus in process of folding down laterally 
its whole carapace, a modification which, as I have shown in some 
detail elsewhere, would lead on to the peculiar organisation of the 
ostracods. I lay stress upon the word ‘whole,’ because if only the 
free lateral flaps behind the head region are folded down, we 
should get a form which might lead on to the other bivalve- 
entomostraca, the Daphnidae and Estheridae. In making these 
suggestions I am again taking up my original position that Apus is 
the protonauplius of authors, and that from it or its young stages 
all the crustacea can be deduced. I may add indeed that nothing 
which has been said during the last five years has shaken me in 
that conviction, based originally upon my study of Apus. On the 
contrary, all the new facts which have come to light have tended 
without exception to confirm it. I refer mainly to the brilliant 
researches of Beecher on the limbs of the Trilobite, 7riarthrus, and 
to these fossil Apodidae now under discussion. 
The whole question, however, must of course be decided solely 
by the evidence; hence, I may remark in passing, it is somewhat 
surprising to find a zoologist declaring that he has no “sympathy 
(sie) with the peculiar phylogenetic speculations of Bernard.” Anti- 
pathy against the views of a fellow-worker, however unscientific 
such an attitude of mind may be, is perhaps excusable, but it is not 
so excusable merely to refer readers to a semi-popular summary 
and not to the papers containing the detailed evidence for the 
hypothesis condemned. Readers could then judge for themselves 
whether these ‘ peculiar phylogenetic speculations’ are speculations 
at all, and not rather necessary deductions from established facts. 
Mr Schuchert’s claim that ‘eyes’ can be faintly seen on the 
specimen will be noticed below. 
DIPELTIS 
The claims of this fossil, of which only four specimens are known, 
to belong to the Apodidae, seem to me far more intricate than are 
those of Protocaris. It appears at first sight as if it might bea 
transition form between Apus and the Trilobites, and yet it only (so 
far as at present known) appears on the scene in the Lower 
Carboniferous, when the Trilobites were already beginning to pass 
away. 
1 “ Apodide,” Section xv., p. 252. 
