G30 
sure of superiiicimihent earth. At times these ehauges 
are very considerable. Of late years, the excavations 
made on the site of the Roman city of llriconium, have 
made these distortions very notorious and produced some 
controversy as to their nature and causes. The mere 
antiquaries have decided that such strang-ely deformed 
heads, with one eye before the other, must have belonged 
to some monstros and unheard of barbarians, who in- 
vaded ]h-itain at the close of the Roman sway and per- 
petrated inhuman cruelties and g-reat devastation. Other 
more curious iii([uirers, admitting to a certain degree the 
true' theory of such contortions, namely, unintermittent 
and long continued pressure, have thought this alone in- 
adequate to effect the changes, and have maintained that 
the carbonic acid of superficial soils dissolves out a certain 
j)ortion of the bone-earth. The author of this hypothesis, 
D:r Henry Johnson of 8hreAvsl)ury, whose memoir was 
lately read before the Royal Society, makes no effort to 
prove that these bones contain less bone- earth than others. 
1 believe that it is not the disappearance of the mineral, 
but of tlie animal constituent of bone, on which its flexi- 
bility dei)ends, that is most intimately connected with 
posthumous distortion. The spheroidal calvarium, the walls 
of which are penetrated with gelatinous matter and its 
cavity filled with slowly decomposing brain, is })laced 
under the most favourable conditions for a change in its 
form, when subjected to permanent })ressure *). And that 
such changes are really and truly posthumous is often 
proved l)y the separation of the bones at the sutures, and 
their further contortion, so that they can no longer be 
adopted to each other at their edges. 
*) Se Cyania Britaiinica, p. 39. 
