Systematic Position of the Sheath-bills. 347 



tlie underlap of the apical portion of the basi-temporal plate 

 and the arrangement of the eustachian tubes tlie Skuas 

 present larine features, the Sheath-hills modified pluvialine 

 ones. Shufeldt (/. c), whom I am once again obliged to 

 quote, states that the basi-temporal region in the Sheath-bills 

 is strongly gallinaceous. This is a statement which I feel 

 convinced could only have crept into the author's manu- 

 script in error, so very far from the actual truth does it 

 appear to be. As regards the palatal plates, pre-palatal 

 bars, maxillo-palatine processes, maxillary processes, and the 

 fenestrse distad of these last — all these, with the exception 

 of the palatal plates, come closer to the like structures in the 

 Skuas than to those of any other Charadriiform groups. 

 The similarity of the arrangement of the maxillo-palatine 

 processes and the presence of the fenestrse distad of the 

 maxillary processes (c/. text-figure 4) in both the Sheath-bills 

 and Skuas is very striking, as are also the disposition of the 

 maxillary and palatal processes of the premaxillse and the 

 form and shape of the maxillo-jugal bars. In the Gulls 

 (Laridae) the fenestrse just alluded to are absent {cf. text- 

 figure 4 C), while the morphology of the maxillo-palatine 

 processes is strongly differentiated from the Skuas. As 

 regards the maxillo-palatine processes, Shufeldt (/. c.) states 

 that these " in Chionarchus minor are much like these bones as 

 we find them in some of the Pigeons.^' I have been through 

 a fair series of Pigeons' skulls in the collection of the 

 British Museum, and I cannot trace the slightest resem- 

 blance between the maxillo-palatines in the two forms, nor 

 can I discover any trace of columbine characters in the 

 osteology of the Chionididae. Referring to the palatal plates 

 once more, these in the Sheath-bills, Gulls proper. Skuas, 

 Oyster-catchers, and Crab-Plover (Dramas) present their own 

 peculiar and respective characters. Those of the Sheath- 

 bills appear to have been much specialised, along with those 

 of Hamatopus, away from the more generalised pluvialine 

 type. There seems to be a Woodcock-like element in both, 

 but this shortening-up of the plates in Hamatopus and 



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