1919-] Cape San Antonio, Buenos Ayres. 525 



seem to be that it is always situated in a junco-bed in a very 

 deep swamp ; that it is invariably and entirely built of 

 the juiico-stems, generally dry, but on one occasion of the 

 green flowering extremities ; that it is not built up from the 

 surface of the water (as I had previously stated), but sus- 

 pended above it at a height of a few to twenty inches ; it is 

 very small, as Hudson mentions, and generally a slight, 

 shallow, platform-structure. But amongst the above, three 

 of a very distinct design were described to me, taken by 

 diff'erent collectors (two of whom were quite trustworthy) 

 and at intervals of many years — 1873, 1892, and 1913. 

 These, though small, were of a cup-shaped formation, and 

 rather neat. It had occurred to me that the weight of the 

 full clutch of five eggs, after a period of incubation, might 

 have caused the interwoven platform, of small pliable stems, 

 to bulge downward ; but on reference to the three instances 

 quoted, only one (consisting of four much-incubated eggs) 

 afforded the possibility; the others were of one and two eggs 

 respectively and quite fresh. So the divergency remains a 

 problem for the present. 



The date varies from 1 October to 8 February, no fewer 

 than three occurring in January. Of the dozen clutches 

 there are four of five eggs each and three of four (much- 

 incubated). As has been said, they are of a very beautiful 

 rich green colouring, particularly when fresh. 



Average measurement of eggs 32 x 26 mm. 



323. Nycticorax obscurus Bp. Dark Night-Heron. 



Male. 11 September. Iris orange. Legs dark blue. 



Male. 11 February. Iris orange-red. Bare parts round 

 eyes, gape, and under mandible green. Upper mandible 

 black. Feet green, claws brown. 



The Night-Heron has held its own in our district ever 

 since I knew it first in 1872, and I confess to the pleasure 

 its presence always affords me as I ride through the swamps. 

 So long as any water is to be fuund at all in a dry season, 

 one or two may be met with at the deeper ponds (it seems to 

 be entirely a freshwater bird, especially as the cangrejales 



2o2 



