About this time Flower began to devote his attention to the mammalian brain; his first contribution on this subject being “Observations on the Posterior Lobes of the Cerebrum of the Quadrumana, with the Description of the Brain of a _Galago_,” of which an abstract appeared in the _Proceedings_ of the Royal Society of London for 1860, although the complete memoir was not published till 1862, in the _Philosophical Transactions_. The date of publication of the abstract proves that these studies were commenced, and the memoir in question completed, before (and not, as stated by Professor M’Intosh,[5] after) the author’s appointment to the Conservatorship of the Museum of the College of Surgeons, which did not take place till the year 1861. The brain of another monkey was also described in a paper on the anatomy of a South American species then known as _Pithecia monachus_, which appeared in the Zoological Society’s _Proceedings_ for 1862. In the following year (1863) he published, in the _Natural History Review_, a still more important communication, dealing with the brain of the Malay siamang (_Hylobates syndactylus_), one of the man-like apes, in which it was shown that in this species (and probably therefore in gibbons generally) the posterior part of the cerebrum, or main division of the brain, overlapped the cerebellum, or hind brain, to an even less degree than in the American howling-monkeys, which had hitherto been regarded as the lowest members of the group, so far as the feature in question was concerned. That such a feature should occur in one of the highest groups of apes was certainly a remarkable and unexpected discovery. Yet another contribution to the same subject was made in 1864, when a paper appeared in the Zoological Society’s _Proceedings_ on the brain of the red howling-monkey, then known as _Mycetes seniculus_, but of which the generic title is changed by many modern naturalists to _Alouata_.