A FISH BRAIN FROM THE COAL MEASURES 159 
in a deep hollow just in front of the lower part of the paroc- 
cipital process, representing the fenestra ovalis auris. In the 
slenderness of the semicircular canals the remains of these organs 
in Scaphognathus resemble the goose, Anser domesticus, as fig- 
ured by Retzius. 
X. THE BRAIN CASTS OF THE TERTIARY MAMMALS 
Brain casts of mammals have long been known and widely 
commented on. Gervais (’69), Marsh (’74), Bruce (’83), Scott 
(98 and 713), Smith (’03), Osborn (10), Palmer (’13) and many 
others have commented on various features of the brain casts 
of Tertiary mammals. All have noted the major features, such 
as the large size of the cerebellum and the apparently smooth 
cerebrum. Scott (98) has called attention to the fact that the 
brain casts are dural casts and as such do not exactly copy the 
eerebral convolutions. Smith (03) and Palmer (718) are the 
first to make an attempt at any neurological study of the brain 
of these interesting vertebrates. Palmer’s paper is the latest 
contribution to the paleoneurology of the mammalian brain; and 
he has given the most careful account which has yet been offered. 
The subject has been touched only in its general features, and 
much certainly remains to be done (fig. 14). A brief review of the 
work which has so far been published on mammalian fossil brains 
will be found in the annotated bibliography. 
XI. SUMMARY 
The earliest vertebrate-like animals, the Ostracoderms, have 
preserved external sensory structures, such as sensory canals, 
lateral eyes, a pineal opening and the opening of the endolym- 
phatic duct. 
The brains of the fishes of the Mississippian and Coal Meas- 
ures are very similar, being identical in a few details. Both 
types are characterized by very large.optic lobes, which in the 
Coal Measures fish was due to the enormous eye. Nearly all 
parts of the Coal Measures brain are known, including some of 
the smaller nerves. The inner ear of one specimen is nearly 
