Anatomy &c. of the Colies. 243 
is hollowed out of a laterally projecting spur. The external 
mandibular condyle is elongate and directed obliquely out- 
wards ; while the internal condyle is also elongate and runs 
parallel with the long axis of the pterygoid. 
Basipterygoid processes are wanting. 
With regard to the articulation of the lower jaw, a curious 
feature is noticeable in the skull of Colivs that I do not 
remember to have seen elsewhere. This is the development 
of a distinct elliptical glenoid surface, for the articulation 
of the internal angular process of the lower jaw. It is 
borne on the antero-inferior angle of the lateral occipital 
wing, mesiad, and slightly candad, of the internal mandibular 
condyle of the quadrate (text-fig. 18, *, p. 241). 
The lachrymal is reduced to a short tear-shaped rod, fused 
with the superior angle of the antorbital plate ; yet Murie 
described a lachrymal in C. lewcotis, which was “nearly 
perpendicular, its inferior limb spongy ... ,” but there was 
no “backward upper orbital process” nor any os crochu. 
Some mistake has probably been made here, as also in the 
statement that the beak joined the skull by a nasal hinge. 
The antorbital plate is large and quadrangular. ‘The 
superior external angle of this plate projects laterad of the 
nasals, and represents the lachrymal, which has fused with 
the plate. 
The mandible has a moderately long symphysis, a large 
lateral vacuity, and a short internal angular process, but is 
abruptly truncated posteriorly. 
The hyoid.—The basihyal is completely ossified and arrow- 
headed in shape, being pointed in front and having the 
posterior angles produced backwards into a pair of spurs 
answering to the ceratohyals; further, the centre of the 
basihyal is perforated by a fan-shaped fenestra. 
The Jbasibranchial is elongated, laterally compressed, 
keeled, and produced backwards into a cartilaginous style— 
the 2nd basibranchial (urohyal). The ceratobranchials are 
relatively short, and so also are the epibranchials. These 
two rods—the cerato- and epibranchials—are subequal in 
length. 
R2 
