272 
BICHAHD ASSHETON. 
I think it is clear from this paragraph that Hiibrecht 
suggests that the separation into the great groups Osteophora 
with larval envelope on the one hand, and Chondrophora, 
Cyclostomata, and Cephalochordata without larval envelope 
on the other hand, dates back to coelenterate days, or at any 
rate to his vermactinian ancestral phase. 
How, then, are we to regard such similarities as the pineal 
eye of Sphenodon and the pineal eye of Geotria ; or the 
first ten pairs of cranial nerves aiad their distribution in an 
Amniote with the ten pairs of cranial nerves of Scyllium ; or, 
in fact, any of the hitherto supposed homologous parts which 
are to be regarded as comparatively speaking recent acquire- 
ments within the phylum Chordata ? Are we not forced to ask 
ourselves. Which of three alternatives are we to accept 
henceforth ? 
(1) That the anatomical resemblances such as those referred 
to above are not true homologies, but are accidental resem- 
blances. 
(2) That tlie coelenterate ancestor “ with a tendency to 
become bilaterally symmetrical,” but not at that time having 
any orgaus at all visibly like the brain, sense organs, kidneys, 
skeleton, etc., of the Lamprey, Elasmobranch or Amniote, 
nevertheless was so constituted internally that its descendants, 
although separating along different lines of descent, as shown 
by the presence and absence of “ trophoblast,” attained 
closely similar results in spite of the divers effects that 
natural selection is known to have had in other divergent 
lines, the Ascidians and Enteropneusts. 
(3) That Hubrecht’s attempt to homologise all such super- 
ficial layers as the trophoblast of Eutheria, 'Geloderm ” of 
Sauropsida, the Deckschicht of Amphibia, of Teleostomes, 
etc., fails. 
Nor does Hubrecht seem to me to meet the objections 
urged by van Beneden, Gadow and others, namely, the many 
characters which unite the three groups forming the Amniota 
and marking them off from the rest of the Vertebrates. I 
may here mention a few and mostly embryological points 
