THE PRINCIPAL BIRD GROUPS 83 



families, some of which are divisible again into 

 sub-families. These are the Otididae or Bustards, 

 the CEdicnemidae or Stone Curlews, the Cur- 

 soriidae or Coursers, the Glareolidae or Pra- 

 tincoles, the Charadriidae or Plovers, Sandpipers 

 and Snipes, the Parridae or Jacanas, the Dro- 

 madidae or Crab Plovers, the Chionididae or 

 Sheathbills, and the Thinocorythidae or Seed 

 Snipes. The number of species contained in 

 this order is nearly three hundred. In point 

 of size the Bustards are by far the largest, 

 some of these weighing between twenty and 

 thirty pounds or more, whilst the Stints may 

 be classed as the smallest, with a body less than 

 that of a Sparrow. There is great diversity in 

 the external characters of the birds composing 

 the present order, and in none more so than 

 the bill. In the Bustards (of which thirty 

 species are recognised) the bill is stout and 

 somewhat flattened, and without the swollen tip 

 characteristic of so many other forms in this 

 order, a peculiarity which is also marked in the 

 short and curved bills of the Seed Snipes, 

 Coursers, and Pratincoles. In the typical Plovers 

 the point of the bill is hard and swollen into 

 what is technically called a dertrum ; in some of 

 the Sandpipers it is hard at the tip (Totaninae) ; 



