140 ROY L. MOODIE 
There is probably a large amount of material preserved in the 
various collections of fossil vertebrates which will add greatly 
to our knowledge of the anatomy of the neural structures of 
vertebrates when this material has been carefully studied. Only 
a few partial attempts have been made to derive the optimum of 
information from the fossil material. Many features, most 
interesting from an anatomical standpoint, are barely mentioned 
in the description of species which has occupied so large a place 
in the paleontological work of the past. 
IV. SENSORY STRUCTURES OF THE OSTRACODERMS 
The most primitive vertebrate-like animals in which any 
indications of sensory structures have been preserved is Both- 
riolepis from the Devonian of Canada and Pennsylvania, one 
of the best known representatives of the fish-like Ostracoderms. 
Traquair’ has described some curious fishes from the lower 
Devonian of Gemiinden in which there are traces of sensory 
structures, such as sensory grooves and eyes. The following 
discussion of the neural structures in the Ostracoderms I owe to 
Professor William Patten of Dartmouth College, and the figures 
will be readily recognized as due to his well-known skill. The 
discussion which follows is taken verbatim from a letter written 
by him January 8, 1915: 
At your request I am sending you two outline sketches of the head 
region of Bothriolepis, showing the probable size and location of the 
brain and principal sense organs. You are at liberty to make use of 
them and the accompanying notes as you see fit. 
It is, no doubt, worth while to put such data as are available into 
visible concrete form, although it is obvious that the presence of a large 
personal factor in reconstructions of this character is inevitable. How- 
ever, if that fact is duly recognized, it is not likely that any harm will 
be done thereby. 
Let me say at the outset that no trace of a brain could be found in 
our dissections of the head, or in the numerous cross and longitudinal 
sections that were made through it. But these fossils, as you know, 
are so beautifully preserved, that the exact form of the head, and the 
minute structure and relations of all the hard parts could be determined 
* The lower Devonian fishes of Gemiinden. Trans. Roy. Soc. Edinburgh, 
vol. 40, pt. IV, pp. 723-739, with plates. 
