182 G. ELLIOT SMITH. 
with Weigert- and Golgi-stained specimens of the adult brain. 
For the opportunity of examining this valuable series T am 
deeply indebted to the generosity of Professor Wilson, whose 
kindly interest and valuable advice I gratefully acknowledge. 
In recording the disposition of parts in a single stage of a 
developing brain, the account, in the absence of other stages 
to show the origin and destiny of the various regions, must be 
almost purely descriptive. This paper, therefore, will indicate 
the apparent differences in the specimen under discussion from 
the ordinarily accepted account, rather than attempt to ex- 
press an opinion upon any of the morphological questions 
raised. Many interesting and important facts are elucidated, 
however, by a comparison with the adult brain, a description of 
whose histology forms the bulk of the thesis of which this 
paper constitutes a part. 
A comparison with some valuable serial sections of foetal 
Perameles and Macropus in various stages of development 
has thrown a considerable amount of light upon many other- 
wise obscure points. These specimens were placed at my 
disposal by Professor Wilson and Mr. J. P. Hill. I have also 
examined some imperfect series of brains of foetal Phalan- 
gista. Several foetal Echidne, which were lately received, 
are unfortunately not ready for examination, but will be 
described subsequently. . 
The literature of this subject is very scanty and incomplete. 
Before the Linnean Society of New South Wales, Dr. C. J. 
Martin and Mr. J. P. Hill recently described the condition of 
the neural plate in the early embryo of Platypus,! and Selenka 
has described early stages of the Opossum brain.? C. L. 
Herrick has published brief notes on, and figured sections of, 
the foetal brain of Didelphys.? Osborn,‘ in his well-known 
paper upon the corpus callosum, described the hippocampal 
‘«On a Platypus Embryo from the Intra-uterine Keg,” * Proceedings 
Linnean Society of New South Wales,’ vol. ix, part 4, 2nd series, p. 736. 
2 * Das Opossum,’ Wiesbaden, 1887. 
> * Journal of Comparative Neurology,’ 1894. 
4 *Morphologisches Jahrbuch,’ Bd. xii, 
