44 Proceedings of the Royal Irish Academy. 
at the upper third are worth describing. The oblique direction of the 
fracture is seen, and an enormous mass of callus has united the frac- 
tured bones into one, obliterating the interosseous space. The upper 
end of the tibia is expanded and hollow, and was, it is probable, the 
seat of a local necrosis. 
Two sacral bones of females were picked up, both of which are 
very crooked, one-half being less developed than the opposite, and the 
coccygeal termination, instead of being in the medial line, is at the side. 
These appear due to some injury sustained in early life. 
Portions of the skull of an idiot were likewise obtained ; they 
possess an unusual amount of interest. The frontal bone shows the 
cranium to have been that of a young person. The orbital openings 
are placed on a different level, the right orbit being considerably more 
elevated than the left. The bone itself is imperfectly developed, the 
entire right half being smaller than the left, and a similar condition is 
recognisable in the occipital bone. A face such as this individual must 
have possessed is delineated in Dr. Robert Smith’s work on ‘“‘ Fractures 
and Dislocations.’”’ It is described as an example of the rare congenital 
dislocation of the lower jaw; and on looking at his plate, and comparing 
it with the frontal bone now found, it is impossible not to be struck 
with their identity of aspect. The subject is so fully worked out by 
Dr. Smith that it is unnecessary to do more than to refer to his ac- 
curate description. He considered this malformation so rare that in 
addition to his own case he records only one other example briefly 
noticed by M. Guerin. The case which Dr. Smith published was that 
of an idiot who died in the lunatic asylum at Island-bridge; the details 
are consequently most perfect. I regret to say that neither the lower 
jaw nor any bones of the face are forthcoming of my specimen, which I 
picked out of a mixed heap of bones thrown together ; so that although 
there is every probability of its being an example of the very rare con- 
genital luxation of the lower jaw, we have only the frontal and occi- 
pital bones preserved, and a portion of the parietal. 
Another idiotic skull, that of a microcephalus, is in perfect preser- 
vation. It has a fairly elevated forehead, is of neat rounded shape, 
but the upper jaw is decidedly prognathous, the lower jaw being 
small and of moderate development ; it resembles in miniature in every 
respect the class of skull which I consider of Celtic or Ivish type, and 
of which I possess several fully developed examples from this find, but 
it measures in circumference only 438 millimetres. The arrest of its 
development has not been caused by synostosis, for the sutures are 
unclosed and perfect, and the age of its possessor is easily calculated, 
as the third molars are still in process of becoming developed. M. Broca 
refers to this class of demi-microcephales ‘‘ all non-deformed skulls of 
males that possess a horizontal circumference of less than 480 milli- 
metres, and of females those under 475 millimetres. Ii belonging to 
Europeans, they should possess an internal capacity below 1150 cubic 
centimetres.” This condition of general or partial arrest of cerebral 
development will commence during the stage of intra-uterine exist- 
