THE PRINCIPAL BIRD GROUPS 59 



the better-known Cormorants. The incubation 

 of these is apparently undertaken by both sexes 

 (the birds standing over them like Auks), and the 

 young are fed for a considerable time. Regular 

 paths to the water's edge are frequently trodden 

 by the birds in going to and leaving their nests, 

 which in some cases are a mile or so from the 

 sea. The largest Penguin known stands about a 

 yard high, the smallest about half that. More than 

 a score species of Penguin are known to science. 

 Considered by some authorities to be some- 

 what closely allied to the preceding, we have 

 now to glance at the Colymbiformes, an order 

 which contains (as two sub-orders) the Divers 

 and the Grebes. These birds, whether so closely 

 related as some recent morphologists think, or 

 not, certainly form an archaic group, and at 

 the same time a very distinct one. The order 

 is one of the smallest in the avine kingdom, 

 the Divers numbering less than half-a-dozen 

 species, the Grebes not more than twenty-five 

 or so. Both Divers and Grebes are eminently 

 aquatic, the feet of the former being webbed, 

 those of the latter furnished with lobes. The 

 legs are situated very far back, whilst the 

 metatarsi are very much flattened a peculi- 

 arity which offers least resistance to the water 



