94, HENRY BURY. 
does not help us: if, with MacBride, we regard it as primitive, 
we directly oppose the paleontological position; if it is 
secondary, Asterids are in the same position as other Echinozoa 
—they retain no trace of aboral fixation.) But after all, have 
paleontologists so completely established their position as to 
compel us to accept it? From the nature of the case no 
details can be known of the internal anatomy of the Cystidea, 
and consequently in connecting them with modern forms we 
are obliged to rely solely on the general arrangement of the 
skeleton, and on the position of the few apertures (mouth, 
anus, &c.) which we can distinguish. The latter seldom help 
us far, while the untrustworthiness of the former is proved by 
the fact, so clearly emphasised by Neumayr (25, p. 497), that 
in order to derive the Echinozoa directly from the Cystids at 
present known, we are compelled to regard the resemblances of 
the skeleton in Crinoids and Echinozoa as due to homoplasy, 
not to homology. Neumayr thinks that the origin of Echinids 
can be very clearly traced through the Cystid Cystocidaris 
(25, p. 400) ; yet his description of this form does not give a 
single really convincing item of homological resemblance, 
while there is much that it is quite as easy to lay down to 
homoplasy as the far more striking similarity of the basal 
plates in Crinoids on the one hand, and Asterids and Echinids 
on the other. 
It is beyond the scope of the present paper to pursue this 
subject further, but I submit that until paleontologists have 
produced some far more striking intermediate forms between 
fixed Cystids and free Kchinozoa than are at present forthcoming, 
embryologists may be forgiven if they do not follow them. 
But even if we deny, on embryological grounds, that the 
Echinozoa ever had a stalk or disc of fixation on the aboral 
surface, there remains the further question whether they may 
not have been fixed, as MacBride supposes, by the preoral 
lobe, which afterwards shifted—in them to the oral side, in 
Pelmatozoa to the aboral pole. Since this actually occurs in 
some Asterids, it cannot be said that this view is so violently 
opposed to embryology as the one we have just been discussing ; 
