Mr. P. R. Lowe on the Crab-Plover. 325 



various well-marked angles with the plane of the long axis 

 of the skull. 



The plane of the whole occipital area in the Gulls, Skuas, 

 and Sheath-bills makes a much smaller angle with the long 

 axis of the skull than it does in Dromas. Thus in the Gulls 

 the occipital area looks almost directly backwards. In 

 Dromas, Charadrius, and Squatarola it looks nearly directly 

 downwards. 



Lambdoidal Ridge. — In Dromas, as also in LaruSf the outer 

 extremity of this ridge bifurcates into two strongly marked 

 divisions^ one pi'oceeding forwards to become merged in the 

 squamosal, the other downwards to form the outer border of 

 the paroccipital process. In Hcematopus, CEdicjiemus, and 

 Stercorarius the condition is more pluvialine — that is to say, 

 the lambdoidal ridge swings abruptly round to form the 

 outer border of the paroccipital process, and the squamosal 

 division of the bifurcation is not so strongly marked. 

 Dromas therefore, in respect of the lambdoidal ridge and, 

 indeed, of the whole occipital area, as well as the'morphology 

 of the squamosal region and the squamosal articulation of 

 the quadrate, is very Larine. 



Supra-occipital Foramina. — In Dromas these are absent, 

 as they are in the Skuas, Gulls, Terns, Sheath-bills, aiul 

 Stone-Plovers. In Hcematopus they are present (or indicated) 

 as they are in the Limicolse generally. 



Cranial Roof. — On a cursory examination, the cranial roof 

 presents a very striking similarity to that of a Gull — the 

 arrangement of the temporal fossae being, for instance, 

 almost precisely similar to what obtains in Larus canus {cf. 

 text-figure 10 B). In Dromas these fossae approach the mid- 

 line even closer than they do in Larus canus, being separated 

 by a space of 4 mm. only, whereas in Larus canus the inter- 

 vening space measures 5 mm. In Hcematopus the temporal 

 grooves fall far short of the mid-line, the arrangement being 

 more pluvialine. In the Stone-Plovers we note a transitional 

 series ranging from a nearly pluvialine condition in 

 CEdicnemus to a complete larine similarity in Orthorhamphus 

 magnirostris. 



