DESCEIPTION OF FIGURES OF SKULLS. 561 



into nearer I'elations with the cavity containing the cerebrum than 

 at either of the two other points specified. The most posteriorly- 

 placed part of the skull, whatever it may he short of an exagger- 

 atedly developed occipital spine, is the point to which the other 

 arm of the compasses is applied for this measurement. This point 

 will sometimes be found at the base and on the upper surface of 

 the external occipital ' spine,' or ' protuberance,' or ' inion,' in cases 

 in which the superior occipital squama is flat and takes a perpen- 

 dicular direction : and here what may be called the ' fronto-inial ' 

 diameter is identical with the ' fronto-postremal ' or extreme length 

 of the skull. It is usually in brachy-cephalic skulls that this is 

 the case ; it is however by no means rare in the dolicho-cephalic 

 forms. Sometimes, as in the more typical dolicho-cephalic skulls, 

 the most posteriorly placed point of the skull is to be found upon 

 the superior squama occipitis, which in these cases is as markedly 

 convex as in the other class of cases it is markedly flat ; and here 

 a difference, which may amount to as much as half an inch, may 

 exist between the 'fronto-inial' and the extreme length. This differ- 

 ence has been considered to furnish a measure of ' occipital dolicho- 

 cephaly^,' or of the extent to which the posterior cerebral lobes 

 overlap the cerebellum. It must be remarked, however, that in 

 some skulls, where we find the occipital spine taking the form 

 of abroad transversely running ridge, in which the linea siipremcB'^ 

 of Merkel are fused with the UneiB superiores miclice, the slightness 

 of the difference between the two cranial measurements in question 

 may cause us to under-estimate the extent of the cerebral overlap, 

 and that, except in those rare cases in which the ' fronto-inial ' 

 diameter can be taken to a ' tuberculum linearum ' as distinguished 

 from a ' protuberantia occipitalis externa,' it is always necessary to 

 compare the internal with the external surface of the skull. 



The extreme breadth has in these skulls been taken upon the 

 parietal bones, either in ' well-filled ' skulls at some point abutting 

 upon the posterior edge of the squamous portion of the temporal 

 bone, or in 'ill-filled' skulls at the tuberosities. The squamous por- 

 tion of the temporal has very frequently in old skulls become sepa- 

 rated a little from the parietal, and it is rendered consequently 



^ For ' Occipital doliclio-cephaly/ see Gratiolet, Bullet. Soc. Anth. Paris, ii. p. 254, 

 1861; Broca, ibid. iv. pp. 49-56, 1863, or his collected Me'moires, ii. p. 27, 1864; 

 British Association Report for 1875, p. 152. 



"- For explanation of these terms, see Dr. Fr. Merkel, ' Die Liuea nucha suprcma,' 

 1871. 



O 



