148 Mr. P. R. Lowe on the 



Scolopax ma,y be due to crowding, consequent on the rotation 

 which has occurred in the skulls of these two forms. 



Premaxillce. — I fail to see any real gallinaceous characters 

 in these. There is a certain superficial resemblance to a 

 gallinaceous form of bill in the Sheath-bills, but this, I 

 take it, is the outcome of functional stress, and is merely 

 convergent in nature. The general shape of the upper 

 mandible in the Sheath-bills has been evolved to suit a 

 particular method of feeding, and is strictly peculiar to 

 them among the Charadriiformes ; but if any comparisons 

 are to be made, they must be made with reference to the 

 bill of the Skuas, which they seem to approach closer than 

 to any other charadriiform type. It must be remembered 

 that the Sheath-bills live amidst rocky, stony, and more or 

 less frost-bound surroundings. They ''pick" their food, 

 and do not bore for it like the Scolopacidse. 



It might be as well to state here that the nostrils of the 

 Chionididse are not holorhinal, as has been stated in the 

 Catalogue of Birds, vol. xxiv. p. 710, evidently through a 

 slip. As is, of course, well known, those of the Gallinae are 

 holorhinal. 



Quadrate. — This bone presents its own peculiar features 

 characteristic of the group, but in the length and form of 

 its orbital process it presents a similarity to that of the 

 Oyster-catchers. The articular facets for the mandible in 

 the Skuas, Gulls, Oyster-catchers, and Sheath-bills present 

 their own distinctive peculiarities, but those of the Sheath- 

 bills agree closer with those of Hcematopus than with the 

 other two groups. 



It is interesting to note that the quadrate in the Skuas 

 and Gulls is distinctly contrasted — for instance, in the 

 posterior surface of the shaft there is in the Gulls (Laridse) 

 a foramen leading into a pneumatic interior ; in the Skuas 

 this foramen is either indicated by a simple depression or 

 is entirely unindicated, the shaft appearing to be non- 

 pneumatic. The shaft of the quadrate is also always 

 relatively longer in the Gulls than it is in the Skuas, and 



