330 DR. GADOW ON THE ANATOMY OF PTEROCLES. [ Mar. 21, 
rhaptes lays four, which in general appearance and so-called structure 
resemble those of certain Partridges. 
The Plovers lay the same number. The Pigeons, on the other 
hand, invariably lay only two; and this is so characteristic of the 
whole group that Bonaparte named them Bipositores. Again, all 
the true Gallinaceous birds produce a great and indefinite number 
of eggs. Therefore in this respect the Sand-Grouse are more nearly 
allied to the Plovers than either to Grouse or Pigeons. 
According to an observation made in the Zoological Gardens of 
London in August 1865, the period of hatching seems to be a little 
more than three weeks : twoeggs were laid at the beginning of August; 
and the young birds came out on the 29th of the same month. 
But one of the most valuable points, as regards the systematic 
position of the Pterocletes, is the fact that the young when hatched 
are thickly covered with hairy down, and that as soon as their plu- 
mage has dried they are able to leave the nest and seek their food. 
This removes them far from the Pigeons, which are the most de- 
cided pedotrophic or gymnogenous of all the birds we know. 
Now to sum up. We have seen that there are many points in 
which the Pteroclide have striking resemblances to the Columbide ; 
but there are also many points in which they approach the Rasores; 
and it is difficult, if not impossible, to made out which characters 
are the more important. 
Prof. Parker was the first to point out clearly that there is a rela- 
tionship between Sand-Grouse and Plovers; and Prof. Garrod, in his 
classification of birds, groups the Columbee, including Pteroclide, 
and the Limicole, including Charadriide, together under his order 
Charadriiformes.. But the Columbide undoubtedly are related to the 
Rasores through such forms as the Cracidee (Peristeropodes, Huxley) 
and the Tetraonide; and, in addition, they are linked together 
by Pterocles and Syrrhaptes. These circumstances show that there 
exists a close relationship between Rasores, Columbz, Pterocletes, 
and Limicole. Phylogenetic tables as a rule are faulty from being 
highly hypothetical, and from the imagination being frequently 
drawn upon in their compilation. However, they can be useful, even 
if they only show where our knowledge is yet insufficient, or why 
systems hitherto made do not agree with more recent ideas. There- 
fore I venture to draw the outlines of a branch of the avian stock, not 
led by preconceived ideas, but solely guided by the consideration of 
facts we know, or at least we have a certain right to believe we know. 
1. Rasores, Columbze, and Limicole are nearer related to one 
another than to the rest of the birds. 
2. If the Columbe approach nearer to the Charadrii than to the 
Rasores, we can express this idea by a stock which gives off two 
main branches :—one for the Rasores ; and another one which again 
soon divides into two—one Columbine, and one for the Plovers (see 
fig. 8). 
3. As the Pigeons have closer affinities to the Fowls than the 
latter have to the Plovers, the Pigeons must be represented by the 
middle branch, that to the extreme left remaining for the Plovers. 
