46 NATURAL SCIENCE |JuLy 
be the proper one for the doubtful group; we may not, for that 
reason alone, boldly assert that they are Marsipobranchs. Nor 
again will it be held to be sufficient in the opinion of most zoo- 
logists to say “ Mr X. was a very gifted man, and he used to say 
that the so-and-so’s are really such-and-such.” It really is time 
for Mr Smith Woodward to give us more solid reasons than such 
as these for classing Ostracodermi with Marsipobranchii. 
I shall be surprised if he can do so; for I have turned the 
matter over carefully and happen to have a rather intimate 
acquaintance with both the Ostracodermi and the Marsipobranchii. 
I am unable to find a single fact which can be considered as 
positive evidence of affinity between the two groups. 
It is true that we do not know of the existence of paired fins 
in the Ostracodermi——nor in Marsipobranchii—but though the 
supposed pectorals of Cephaluspis are probably not to be regarded 
as pectorals, we are not in a position to assert that Pteraspis had 
no lateral fins, nor that the ‘flippers’ of Pterichthys do not 
represent such organs. 
Before the proposition favoured by Mr Smith Woodward could 
be seriously discussed in the terms in which it is stated, it 
would be necessary to show that the Ostracodermi are a natural 
group, and no one can pretend that this is the case. The Cepha- 
laspids, the Pteraspids, and the Pterichthyids were originally asso- 
ciated as ‘ Ostracodermi’ for purposes of mere temporary con- 
venience. It is a question whether in these days of an avowed 
genealogical implication in our classifications, such ‘ lumber- 
rooms’ as ‘ Ostracodermi’ are permissible. I think not. There 
is absolutely no reason for regarding Cephalaspis as allied to 
Pteraspis beyond that the two genera occur in the same rocks, 
and still less for concluding that either has any connection with 
Pterichthys. 
If, in view of this fact, we consider in a more detailed way the 
suggestion of Cope, acclaimed by Smith Woodward, we find that it 
amounts to the assertion, that there are evidences of the close genetic 
relationship of the Marsipobranchii with ether the Cephalaspids, or 
the Pteraspids, or the Pterichthyids—or possibly with all of them. 
So far as I am aware the only satisfactory evidence of marsi- - 
pobranch affinities which one could expect to be offered by fossil 
remains of paleozoic date, is the presence of a single median nasal 
aperture. The characteristic monorrhine structure of the marsi- 
pobranchs might have been recorded in the preserved remains of an 
armoured marsipobranch, had such a creature ever existed. Is there 
any evidence of such asingle nostril in Pteraspids, or Cephalaspids, or 
Pterichthyids ? Most assuredly there is not. There is no aperture in 
the cephalic shields of any of these forms which can be assigned to 
