8 Osteology of Circus hudsontus. 
The vomer (Fig. 5) can best be studied in a longitudinal and 
vertical section of the skull, passing very slightly to one side of 
the median line. This I have been enabled to perform on one 
skull by means of an exceeding fine jeweller’s saw. ‘The appear- 
‘ance upon the cut side of such a section is well seen in the figure 
referred to, where the position of the vomer, there marked v, can 
be easily observed. It is seen to be a thin lamina of bone, flat- 
tened from side to side, and shaped much like a long / Its 
anchylosis with the united palatines seems to be complete, while 
its anterior extremity is pointed at:d free. The maxillo-palatines 
have already been fully described above, their relation to the 
inter-nasal septum and 
the vomer can also be 
seen in Fig. 5. 
The piterygoids are a 
very slender pair of bones 
in Cz7cus,; anteriorly they 
articulate with the pala- 
tines and the rostrum of 
the sphenoid, although 
they fail to come in con- 
Fig. s. <A vertical, longitudinal section of the skull cf sac with a other ae 
tc hoy We Shee ete ace te 
‘Boutepaminedens ee 
panded and cup-shaped 
to allow them to articulate with a corresponding convexi.y on 
each quadrate. They do not meet the basi-sphenoid by articula- 
tion with basi-pterygoid processes developed on the part of that 
latter bone, as we see them in the owls (Szvrza, Speotvio, and 
others). At the points, however, where such processes are de- 
veloped, Cz7caws possesses a sharp-pointed spicula of bone on either 
side, and this 1s opposite a corresponding enlarged part of each 
pterygoid (Fig. 3). These two projections are separated from 
each other by at least two millimetres in life, 7. ¢., the pointed 
rudimentary basi-pterygoid process and the enlargement on the 
eorresponding pterygoid 
The basi-temporal and basi-occipital regions are well depressed 
(viewing the ssull in the position of Fig. 3) below the exoccipital 
regions and other surrounding parts. A thin lip of bone over- 
hangs the openings, which are here separate Eustachian, tubes ; 
