Zoological Society. 57 of a few instances, were we to take the eggs of our British birds as our only guide, we should arrive at the best and most approved ar-rangement of the different genera." I am aware that exceptions and discrepancies may be pointed out. The colour deposited on the egg-shells is an animal matter, depend-ent on the health of the bird. Fear or confinement acting consti-tutionally upon the organs of secretion are known to affect this colouring-matter. The greatest amount of variation is found to occur among the Larida. With these preliminary remarks, I proceed to the description of a collection of eggs of some of the birds of Chile, obtained by Mr. Bridges, and exhibited here by Mr. Cuming. Cathartes Iota of Molina ; Chilian name Iote. — The egg of this Vulture measures 2 in. T 8 ^ in length, and 1 in. t 9 q in breadth : the shape is rather peculiar, being broadest at the centre and tapering gradually in both directions, so as to become pointed at both ends. The ground colour is white, slightly tinged with red ; blotched with pale red ; spotted and speckled with dark brownish red. Haliaetus aguia, Temminck ; Aquila of the Spanish ; Calquin of the Indians. — The egg is 2 in. ±± in length by 2 in. ^ in breadth ; elliptic ; white, with a few spots of dark red and numerous spots and speckles of pale red. Polyborus Brasiliensis, Swainson ; Chilian name Traro and Taro. — The egg of this bird is 2 in. T 4 ^ in length by 2 in. in breadth ; blotched, spotted and speckled with dark red, on a ground of reddish white. This egg, in its colour and markings, resembles those of our British Osprey. Milvayo pezoporos, Meyen ; Chilian name Tuique. — The egg mea-sures 1 in. T 8 y-by 1 in. -fa ; white, tinged with red ; blotched, spot-ted and speckled with dark brownish red. Strut pratincola, Bonap. ; Strix flammea of Wilson; Strix Ameri-cana of Audubon. Screech Owl. — The egg is pure white, and mea-sures 1 in. -i-J in length and 1 in. T 4 ^ in breadth. Tardus Falklandicus of Quoy and Gaim . ; Chilian name Torzal. — This egg closely resembles those of our British Missel Thrush. The ground colour pale bluish white, spotted and speckled with pale red. The length 1 in. -fa, the breadth three-quarters of an inch. Geositta canicularia of Vieillot ; Chilian name Caminante. — The egg is pure white, and measures ■£$ of an inch in length by T ' ff of an inch in breadth. Cyanotis omnicolor, Swains. ; Chilian name Pojaro. — This small egg measures only ^| of an inch in length by half an inch in breadth ; of a pure and spotless white, but some specimens of the eggs are tinged with pale buff-colour. Crithacjra brevirostris, Gould ; Chilian name Chirique. — The egg is white, tinged with green, speckled with brownish red, and mea-sres -fa of an inch in length by half an inch and -^ in breadth.