•'U4 SEXUAL SELECTION: MAMMALS. Pabt II. 
number, though very variable in distinctness. From 
this condition there is hut a very small step to the 
complete absence of spots at all seasons in the adults; 
and lastly, to their absence at all ages, as occurs with 
certain species. From the existence of this perfect 
series, and more especially from the fawns of so many 
species being spotted, we may conclude that the now 
living members of the deer family are the descendants 
of some ancient species which, like the Axis deer, was 
spotted at all ages and seasons. A still more ancient 
progenitor probably resembled to a certain extent the 
Hyomoschus aquaticus — for this animal is spotted, and 
the hornless males have large exserted canine teeth) 
of which some few true deer still retain rudiments. It 
offers, also, one of those interesting cases of a form 
linking together two groups, as it is intermediate in 
certain osteological characters between the pachyderms 
and ruminants, which were formerly thought to be 
quite distinct . 41 
A curious difficulty here arises. If we admit that 
coloured spots and stripes have been acquired as orna- 
ments, how comes it that so many existing deer, the 
descendants of an aboriginally spotted animal, and 
all the species of pigs and tapirs, the descendants of 
an aboriginally striped animal, have lost in their adult 
state their former ornaments ? I cannot satisfactorily 
answer this question. We may feel nearly sure that 
the spots and stripes disappeared in the progenitors of 
our existing species at or near maturity, so that they were 
retained by the young and, owing to the lawof inheritance 
at corresponding ages, by the young of all succeeding 
generations. It may have been a great advantage to 
41 Falconer and Cautley, ‘ Proc. Geolog. Soc.’ 1813 ; and Falconer’s 
1 Pal. Memoirs,’ vol. i. p. 196, 
