296 
the latter for „Schaltknochen.‘“ HRDLICKA (8) gives a nice theory to 
explain the sut. par. which also runs over the squamosum. 
According to VIRCHOW, sutures in a piece of bone admit a stronger 
growth, so much as is limited by the suture, and this growth especially 
takes place with right angles on this suture. If we now take a vertical 
sut. par. on a skull, than the parietale will become ,,longer“ by it. 
Now, if this “lengthening” is prevented by a fixed articulation of the 
parietale more or less grown together with the squamosum, then a 
pressure arises on the squamosum and in these circumstances a push, 
blow, or the pressure itself can give occasion to the origin of a cleft 
in the squamosum, as the continuation of the vertical sut. par. The 
other bones of the skull are connected by zigzag sutures and besides 
they are stronger. This 
is the reason why on 
these bones the con- 
tinuing of the sut. par. 
occurs much less. Only 
once — in Macacus rhe- 
sus — HRDLICKA saw 
thatasut.par.continued 
its course on the frontal 
bone. Untilnow other 
cases of this abnorma- 
lity are not yet known. 
Fig. 3. If now we do find the 
sut. par. verticalis on 
a skull and the dividing of the squamosum is wanting, then this is 
more or less against the expectation but it might be explained by the 
casual strength of the squamosum either because the articulation of 
it with the parietale is free, has some play, room, or because these 
two causes co-operate. So far this theory, which though mechani- 
cally right, must still be tested at more material. 
Cebus albifrons. (See fig.3.) ,,Museum van Natuurlijke Historie 
at Leiden. Cat. No. 6. v. sp. cat. No. 3. The thus inscribed skull 
is complete, with loose lower jaw. The horizontal sut. par. begins 
in a curve of the sut. coronalis near which we also find an opening 
which has perhaps originally contained an ossiculum Wormianum. 
The connection of such a separate little bone with the commencement 
of the sut. par. has already been found before, a. 0. by HRDLICKA 
