ShUFKLDT: OSI-KOLUGV OF I'HK LiMICOL/li. 25 



exlL'inall) , and is very thin in ,/',". niontixna — thicker in the (lolden 

 Plover. A large vacuity absorbs almost entirely the interorbital sep- 

 tum below, merging with the foramen rotundum behind. Separated 

 by an osseous horizontal lamina, there exists above this another large 

 vacuity, the forward extension of the foramina for the first pair of 

 cranial nerves, which are greatly increased in size. 



At the back of the cranium there is a fairly well pronounced supra- 

 occipital prominence pierced upon either side by an o\al foramen. 



tn examining the base of the cranium in a young chick of the 

 Killdeer Plover (,:£. vocifera') I observe that the bony bridge that lies 

 between the supra-occipital foramina is formed by the sujjra-occipital 

 itself; it is cleft above at this stage, and stouter lateral masses are seen 

 on either side of it. The basi-temporal is still distinct as an element, 

 as are the ex- and basi-occipitals. At the side we find that the squa- 

 mosal sends upw^ards an ascending process, long and slender, which 

 overlaps the posterior third of the rounded margin of the frontal, and 

 itself makes the periphery of the orbit. This bone below develops a 

 " zygomatic process," marked by a semicircular nick at its extremity, 

 which arches over the articulation for the quadrate. In adults a sphe 

 notic process is fully developed. The occipital condyle is small and 

 circular, with the notochordal notch nearly obliterated. 



\\'ith respect to the quadrate, it is peculiar only in having its pro- 

 cesses and shaft much compressed and plate-like. The orbital spur, 

 making up nearly half the bone, is a quadrilateral lamina, with its base 

 applied to the entire length of the body of the shaft of the quadrate 

 proper. A long narrow condyle surmounts the otic process, placed at 

 right angles to this orbital offshoot, and the pit for the quadrato-jugal 

 occupies the summit of the outstanding lateral mandibular process. 

 Rather undue shortening takes place in the shaft of a pterygoid, owing 

 to the far backward reach of the palatine and the great size, on the 

 other hand, of the quadrate. Basi-pterygoidal processes are present and 

 articulate with facettes at the base of the sphenoidal rostrum. 



The hyoidean arches are very delicately constructed, but present 

 nothing peculiar ; they are described for other limicoline birds be- 

 yond. 



The mandibular elements fuse together early in all true plovers, and 

 in the chick the ramal fenestra is not obvious, whereas, as the bird ma- 

 tures, a small slit-like opening makes its appearance. 



The posterior angular processes of the lower jaw are recurved 



