COCOI HERON 93 



deal, but chiefly the Cocoi, and think there is some- 

 thing to be said in support of Buffon's opinion that 

 they are wretched, indigent birds, condemned by 

 the imperfection of their organs to a perpetual 

 struggle with want and misery. In reality the organs, 

 and the correlated instincts, are just as perfect as in 

 any other creature, but the Heron is certainly more 

 highly specialised and lives more in a groove than 

 most species. Consequently when food fails him in 

 the accustomed channels he suffers more than most 

 other species. 



Much as the different species vary in size, from 

 the Ardea cocoi to the diminutive Variegated Heron 

 of Azara (Ardetta involucris), no bigger than a Snipe, 

 there is yet much sameness in their conformation, 

 language, flight, nesting and other habits. They 

 possess a snake-like head and neck, and a sharp 

 taper beak, with which they transfix their prey as 

 with a dart also the serrate claw, about which so 

 much has been said, and which has been regarded as 

 an instance of pure adaptation, 



A curious circumstance has come under my obser- 

 vation regarding Herons. Birds in poor condition are 

 very much infested with vermin ; whether the ver- 

 min are the cause or effect of the poor condition, I do 

 not know ; but such is the fact. Now in this region 

 (the Argentine Republic) Herons are generally very 

 poor, a good-conditioned bird being a very rare 

 exception; a majority of individuals are much 

 emaciated and infested with intestinal worms ; yet I 

 have never found a bird infested with lice, though the 



