1832. ] DR. VAN DYCK ON SYRIAN STREET-DOGS. 369 
causes; and these modifications of structure &c. differ in different 
species under apparently the same conditions. Statements of this 
nature have sometimes been misinterpreted, as if it were supposed 
that variations were indefinite or fluctuating, and that the same 
variations occurred in all species. 
In reference to sexual selection, I will here only add that the 
complete manner in which the introduced dogs and other domestic 
animals in South America and other countries have been mongrelized, 
so that all traces of their original race have been lost, often appeared 
to me a surprising fact. This holds good according to Rengger' 
with the dogs even in so isolated a country as Paraguay. I formerly 
attributed this mongrelization merely to the breeds not baving 
been kept separate and to the greater vigour of cross-bred off- 
spring; but if the females often prefer strangers to their old 
companions, as seems to be the case, according to Nordenskiéld, in 
Siberia, and in Syria as shown in the following essay, then we can 
readily understand how rapid and complete would be the progress of 
mongrelization. I will now give without further comment the essay 
which Dr. W. Van Dyck, Lecturer on Zoology to the Protestant 
College at Beyrout, who has had excellent opportunities for obser- 
vations during a residence of twenty years, has been so kind as to 
send me. 
On the Modification of a Race of Syrian Street-Dogs by means 
of Sexual Selection. By W. Van Dycx, M.D. 
Beyrout is one of the principal ports on the Syrian coast, and has 
a population of from eighty to one hundred thousand. Like most 
Oriental cities, its system of street-cleansing is far from perfect, and 
much of the scavenging is left to the street-dogs, many hundreds of 
which roam at large through the town and suburbs, picking up a sub- 
sistence as they best can. Twenty years ago, and previously, these 
dogs were quite a homogeneous. race, the following being a rough 
description of a typical specimen :—height at shoulder, 20-22 in. ; 
length from muzzle to root of tail 32-34 in. ; length of tail, 12-15 in. ; 
colour sandy grey, with some variety of shades (rarely so light as to 
pass for dirty white), in most cases distinctly darker above than 
beneath, and not unfrequently grizzled or brindled ; head of medium 
size, with rather pointed snout and small pointed semipendulous ears ; 
tail bushy, usually carried up over the back, sometimes much curled ; 
general aspect decidedly jackal-like, or semi-wolfish ; disposition 
cowardly, seldom savage. The only departures worthy of mention 
from the above type, at the time of which I write, were occasional 
black dogs, mostly with shorter hair than that of the sandy ones, 
rarely piebald black-and-white specimens. At the present date, the 
case is very different. The sandy-grey colour still prevails, it is true ; 
but there is hardly an imaginable colour or combination of colours 
' ‘ Naturgeschichte der Saugethiere von Paraguay,’ 1830, p. 154, 
25* 
