No. 409.] THE SAND GROUSE. I5 
note that in Syrrhaptes there are sixteen cervical vertebrae; 
fifteen in Pterocles arenaria; and but fourteen in Lctopzstes 
migratorius. Again, in Syrrhaptes, three of the dorsal verte- 
brze coóssify into one piece, the fourth dorsal remaining free. 
This agrees with Ectopistes; while in Pterocles arenarius, 
four dorsals coóssify to form a single piece, and posterior to 
this another free dorsal vertebra is found, making five. This, 
with many similar points in its skeleton, goes to show that 
Syrrhaptes is nearer the pigeons than is Pterocles; yet neither 
of these forms are truly columbaceous. 
In the pelvis of either genus we find just such a bone as we 
should expect to find in birds that are doubtless typical inter- 
mediates, standing directly in their organization between two 
well-circumscribed groups. In the sand grouse, however, the 
lateral portions of the pelvic sacrum, at its widest part, fail to 
ossify, and thus, in the dried skeleton, leave large vacuities in 
that region not seen in tetraonine nor typical columbine birds. 
There is usually one less sacral vertebra in pigeons than there is 
in the sand grouse, the former having fourteen, while Syrrhaptes 
and Pterocles have fifteen ; and Parker claims that the last has but 
six vertebrae in its tail, and this is all I find in Ectopistes, while 
Columba livia and Pterocles arenarius each possess seven. 
Professor Parker is correct when he says, “I do not set 
much value on the number of caudal vertebrz, as the last is 
a series, and the tail is very apt to vary in the number of those 
which shall be swallowed up in this terminal piece.” 
The epipleural processes on the ribs are much broader and 
deeper in Pterocles arenarius than they are in Ectopistes and 
other pigeons.! : 
In Pterocles the scapula are long, narrow, and tapering, 
reaching, in fact to some extent overreaching, the ilia of the 
pelvis posteriorly. In Ectopistes these bones are cimeter- 
1 In the autumn of 1899 Professor C. O. Whitman requested me to write out 
for him a complete account of all the species of the North American pigeons, in 
so far as their osteology was concerned, as a contribution to the Journal of 
Morphology. This I did, illustrating the memoir with several figures of the bones 
of the birds of that group, and a number of the points referred to in the present 
paper will therein be illustrated. It was accepted for publication and will in due 
course appear in the aforesaid journal, probably some time in 1901.— R. W. S. 
