60 THE STRUCTURE OF MAN 
Fig. 41, +). Thomson, from the study of a large series of 
skulls, has shown good reason for regarding this as one of the 
series of Wormian bones which so often occur in this region, 
and for believing it to arise by dismemberment from either the 
alisphenoid or parietal.]* 
The nasal bones which, as a rule, remain distinct, sometimes 
fuse to form one bone. This occurs far more frequently in the 
lower races (Patagonians and tribes of South Africa) than in the 
higher; and it is the more probably an atavism, since this fusion 
is normal in Apes. In the Chimpanzee it takes place as early as 
the second year. 
The lachrymals are susceptible to not a few variations, and 
very rarely an abnormal enlargement of the hamular process 
causes these bones to appear at the surface of the face, as in 
many lower Mammals (Gegenbaur). 
Many variations are to be found in the bones of the inner 
orbital wall. For example, the lachrymal bone may be altogether 
wanting, or only present in a vestigial form, so that the os planum 
(lamina papyracea) comes into direct contact with the ascending 
or nasal process of the upper jaw (premaxilla). In other cases 
the lachrymal bone may be divided into an upper and a lower 
portion by a suture, and there are other variations to which it 
and the development of the hamular process are susceptible; it 
may be occasionally replaced by a radially disposed series of 
small bones. 
A similar division of the os planum of the ethmo-turbinal 
into several pieces has been observed (Turner, Macalister, Arthur 
Thomson); but it is questionable if any morphological signi- 
ficance is to be attached to these variations. 
According to the cousins Sarasin, a lower stage of develop- 
ment is shown in the skulls of the Veddahs and others, in the 
downward prolongation of the nasal portion of the frontal bones 
into the orbits, which he very close together and are spacious, 
1 [(Jour. Anat. and Phys., vol. xxiv. p. 856). I have elsewhere pointed out (2b7d., 
vol. xxiv. p. xviii.) that the ossa preinterparietalia lie within the area normal to the 
parietals, and that therefore these, at least, among the intercalary elements of the 
cranium, may be similarly referred to an origin from those bones, by dismemberment, 
under the expansion of the brain case. The phenomenon appears to me akin to that 
of the well-known double ossification of the supra-occipital in its most expanded 
form (ex. Cetacea and some Insectivora), and of the occasional duplication of the 
lachrymal, and of the os planum, itself already intercalated in the orbital wall in 
the Primates. (My friend Dr. Forsyth Major has lately shown me that the Lemurs 
do not differ from the higher Primates in the absence of the latter character, as is 
generally believed).—G. B. H.] 
