154 On the Systematic Position of the Sheath-bills. 



relics of a once-existent series of continuously iutergrading 

 forms, but it is stranger to reflect how extremely difficult 

 it is to put one's hand upon what might be termed truly 

 intergrading links. 



With a view to investigating the question as to whether, 

 if we went far enough back in time, we should find genera- 

 lised forms of Gulls and. Limicolse which would disprove 

 such suggestions as have just been tentatively put forward^ 

 I have lately examined the collection of fossil Charadrii- 

 formes in the British Museum collection. So far as one 

 can form an opinion from the material available, a Gull 

 or a Tern was nothing else than a Gull or a Tern as far 

 back at least as the Upper Oligocene (cf. Larus (? Sterna) 

 eleyans Milne-Edwards). Again, a Sandpiper was a Sand- 

 piper and nothing else (cf. Totanus majori Lydekker or 

 Trinya gracilis Milne-Edwards) ; a Spur-winged Plover was 

 a Spur-winged Plover, and so on. On the other hand. 

 Marsh has described Palceotringa from the Cretaceous 

 Shales of Kansas, which, if really a generalised limicoline, 

 seems to controvert such ideas. The fact, too, that the 

 Skuas ill their cranial characters seem more generalised in 

 the direction of the Plovers gives one pause to think ; but 

 such instances do not affect the fact that, although there 

 may be a series of progressive steps, it does not necessarily 

 follow that there Avere links connecting such steps. But 

 whatever the truth may be as regards the mode of origin of 

 such charadriiform groups as the Sheath-bills and others, 

 the outstanding fact which has impressed me is that, in so 

 far as their osteological characters are concerned, there is 

 very little real difference between a Gull and a Plover, 

 and certainly very little fundamental difference that can be 

 expressed on paper. The statement that a Gull is only a 

 highly specialised Plover is, I fancy, regarded by most 

 ornithologists as a mere academic expression of a somewhat 

 hazy idea. It is, in reality, a very literal and patent fact. 



Finally, I may, perhaps, be permitted to quote Shufeldt's 

 summary of his findings in regard to the osteology of the 

 Sheath-bill (Journ. Anat. & Phvs. Lond. xxv.) : — 



