THE DUNLIN 467 



between the two points of contact, afford a clearer idea of the form 

 and consistence of hidden objects." 



When the bird, after repeated tapping and probing, receives the 

 expected indication of the presence of a living animal, it quickly 

 sinks its bill deeper into the ground until it comes in contact with the 

 object of its search. So far the slightly separated mandibles remain 

 nearly parallel, but on contact with the capture the terminal part 

 of the upper mandible actuated by certain specialised muscles is 

 expanded. 1 If the animal is small, such as a tiny crustacean or 

 mollusc, it may be captured and swallowed before the bill is entirely 

 withdrawn, but " if contact is made with a worm the bill is propelled 

 downwards over the upper end of the worm by a number of quick 

 thrusts, the mandibles being separated during the thrusts and closed 

 tightly on the worm between each, when the reverted cusps on the 

 palate and the edges of the mandibles prevent the worm from slipping 

 back into its burrow." 



Considerable controversy has taken place at times with regard 

 to the small southern race of the dunlin, named as a distinct species 

 by Brehm Tringa Schinzii, a name which belongs properly to 

 another species. There is evidence to show that most, if not all, of 

 the dunlin that nest in the British Isles belong to the small form, 

 while the northern breeding birds which come to us in autumn and 

 stay through the winter are of the larger form. There is, however, 

 no clear line of demarcation between the two forms, either as regards 

 size or distribution. Measurements of a number of specimens show 

 that there is every gradation between the extremes. 3 



1 For an article dealing with these muscles, see Ibis, 1893, p. 361. 



* J. M. Dewar, ' Notes on the Feeding Habits of the Dunlin," Zoologist, 1901, pp. 1-14, from 

 which all the information relating to the feeding-habits of this species on pp. 465-7 is culled, 

 except when otherwise stated. 



3 Mr. Backhouse, writing in the Zoologist, 1901, pp. 91-94, gave some bill and wing measure- 

 ments of the large and small forms : 



Bill. Wing. 



Small form, .... '99 to 1 '2 4'1 to 4'15 



Large form, . . . . 1'4 to 1'27 4-55to4-75 



All the large ones were from the sea-coast and the small ones from the " fells," and pre- 

 sumably therefore breeding birds. 



