In this subfamily the lacrymals are free but have prominent outjutting processes and are not rounded and merged in the line of the orbital rim as in the Charadriinae. There is no foramen for the passage of the nasal duct.
The subfamily contains five genera represented within our limits, the species of which cover practically the whole world. Since the first edition of the ' Avifauna of British India' was written, there is no other group of birds in which so many drastic changes have been made in classification and in the splitting-up of genera. This splitting-up has now been admitted by most systematists to be necessary and it is accordingly accepted by me. Squatarola and Pluvialis have been shown by Lowe to be not only different genera but to be members of different groups, whilst the genus Charadrius, which formerly contained all those little Plovers of the Ringed Plover and Kentish Plover types, has been divided into no fewer than five genera, although, superficially, they appeared to be so closely allied.
Key to Genera.
A. Bill moderate, not longer than head; tarsus reticulated behind.
a. Bill conical, culmen flattened, no swelling at tip…………ARENARIA, p. 153.
b. Upper mandible swollen near tip.
a1. A hind toe …………SQUATAROLA, p. 156.
b1. No hind toe.
a2. No white ring round neck…………EUPODA, p. 158.
b2. A white ring round neck…………LEUCOPOLIUS, p. 160.
B. Bill long; tarsus reticulated throughout…………HAEMATOPUS, p. 164.