12 MARY L. WALKER ON THE FORM OF 
ScHIzZOoGNATHA : I.—CECOMORPH”. 
This is one of the more polymorphic groups, and we have studied the quadrate 
in four members of its principal types, the Petrel (and Albatross), the Grebe, the 
Razorbill, and the Gull. 
In the Fulmar Petrel (Procellaria glacialis) the quadrate is short and broad. 
The capitula are small, rounded, and distinctly separate. The anterior process is of 
PROCELLARIA GLACIALIS. 
moderate size. The quadrato-jugal cup is well marked, and placed low down at the 
postero-inferior angle. The pterygoid condyle is imperfectly severed from the mass 
of bone below. The mandibular articular surface has a large accessory trochlea on 
the outer sides of its anterior condyle, and the posterior portion is transversely 
elongated, and its external half is somewhat hollowed out. 
The Albatross is quite similar to the above. 
In the Grebe the quadrate is more delicately formed. The capitula are small, 
the anterior process very long, and the pterygoid condyle distinct. The quadrato- 
Fig. 22. PoDICEPS CRISTATUS. 
jugal cup is more nearly in the middle of the inferior border of the bone. The 
anterior mandibular condyle has a very perfect external accessory trochlea. 
In the Gull the bone is broad, but with a slender neck. The capitula are 
rather more deeply cleft than in the former species. The anterior process is short, 
ig. 23. LAaRUS INOANUS. 
