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its first trace of bone after birth. Grandidier and Filhol (8), in tlieir 

 examination of the skull of an extinct hippopotamus (H. 1 e m e r 1 e i) from 

 Madagascar, found a small independent ossicle, on both sides of the 

 head, included between the lachrymal, nasal, and maxillary bones. 

 They were led by this discovery to examine other skulls of hippopo- 

 tamus in the Museum of Paris; but in no adult specimen was any 

 ossicle demonstrable. On both sides of the skull of a very young 

 hippopotamus from Senegal, however, they found a small elongated 

 piece of bone completely separating the lachrymal and nasal bones. 

 On the left side the ossicle was contracted in the middle by a pro- 

 montory from the lachrymal: from which, and from further evidence 

 afforded by a somewhat older skull, they concluded that the ossicle 

 represented a true prefrontal capable of division into two parts, the 

 upper of which may either disappear or fuse with the frontal. 



Grandidier and Filhol's assertion that there is a fusion between 

 the supernumerary ossicles and the frontal bones in the hippopotamus 

 is supported by the condition in a specimen in the Museum of Queen's 

 College, Belfast. Of this, Cunningham (9) says that the small bones 

 "are distinctly indicated, though the suture separating them from the 

 frontals is to a considerable extent obliterated". 



Additional examples in mammals other than Man are given by 

 Cunningham. On each side of the skull of a young lemur he found 

 a triangular bone occupying "a position corresponding with the pre- 

 frontals in Lizard and Crocodile", and with a suture clearly defining 

 its limits (9). He also found bones similar to those in the lemur in 

 an adult Macropus giganteus (10). In this case only the bone 

 on the right side was recognisable as a distinct ossification, while on 

 the left side the suture between it and the lachrymal had disappeared. 

 Cunningham, further, found the bones on both sides of the skull of 

 an adult wombat (Phascolomys platyrhinus) distinctly separated 

 from the frontal, nasal, lachrymal, and maxillary bones. 



That accessory ossicles about the lachrymal bone occur with some 

 degree of frequency in lemurs is shown by the observations of Forsyth 

 Major (11) who found what is undoubtedly an Ossiculum maxillo- 

 frontale in Perodicticus geoffroyi and P. calabarensis. In 

 the former, the ossicle was of good size and completely isolated from 

 the lachrymal, frontal, and maxillary bones, between which it was 

 situated. In P. calabarensis the ossicle was very much smaller 

 and it is "on its way to become soldered to the frontal". 



From the above it is clear that an Ossiculum maxillo-frontale is 

 of wide-spread occurrence. In those animals in which there is a large 



