OlUP. IV. 
MANNER OF DEVELOPMENT. 
125 
quently in ancient, than in recent crania, especially as 
Canestrini has observed in those exhumed from the 
Drift and belonging to the brachycephalic type. Here 
again he conies to the same conclusion as in the ana- 
logous case of the malar bones. In this and other 
instances presently to be given, the cause of ancient 
races approaching the lower animals in certain cha- 
racters more frequently than do the modern races, 
appears to be that the latter stand at a somewhat greater 
distance in the long line of descent from their early 
semi-human progenitors. 
Various other anomalies in man, more or less analo- 
gous with the foregoing, have been advanced by dif- 
ferent authors 37 as cases of reversion; but these seem 
hot a little doubtful, for we have to descend extremely 
low in the mammalian series before we find such struc- 
tures normally present . 88 
17 A whole series of cases is given by Isid. Geoffroy St.-Hilaire, 
1 Hist, des Anomalies,’ tom. iii. p. 437. _ 
38 In my ‘ Variation of Animals under Domestication (vol. n. p. oi) 
I attributed the not very rare cases of supernumerary nmnnnse in 
Women to reversion. I was led to tills as a probable conclusion, by the 
additional mammas being generally placed symmetrically on the breast 
and more especially from one case, in which a single efficient mamma 
occurred in the inguinal region of a woman, the daughter ot another 
Woman with supernumerary mamma). But Prof. Preyer v er vamp 
run das Dascin,' 1869, s, 45) states that mammas erratic® have been 
known to occur in other situations, even on the back ; so that the lurce 
of mv argument is greatly weakened or perhaps quite 
With much hesitation I, in the same work (vol. u. p. 1-), attributed 
the frequent cases of polydact.ylisni in men to revcisum. "a P ar 7 
led to this through Prof. Owen’s statement, that some ot the Ichthy- 
optorygia possess more than five digits, and there ore, as I supposed, had 
retained a primordial condition; but after reading Piof._ Gegcnbaur s 
Paper (‘ Jcuaiseheu Zeitsckrift,’ B. v. Heft 3, s. 341), who is the highest 
authority in Europe on such a point, and who disputes Owen s con- 
clusion, I see that it is extremely doubtful whether supernumerary 
digits can thus be accounted for. It was the fact that such digits not 
only frequently occur and are strongly inherited, but have the power 
of regrowtli after amputation, like the normal digits of the lower verte- 
