390 Recently published Ornithological Works. 
Mr. H. D. Astley’s paper on Lear’s Macaw, and Mr. D. 
Seth-Smith’s on the plumed Doves are each accompanied by 
a coloured plate, in the latter case of Lophophaps leucogaster ; 
while that of Mr. Meade-Waldo on the Cruise of the ‘ Valhalla’ 
has an illustration of Jackass-Penguins and the young 
Sacred Ibis. Several other articles, with the usual notes, 
reviews, and correspondence, give evidence of the lively 
interest taken by many persons in the Magazine and its 
contents. 
28. Bonhote on Coloration in Mammals and Birds. 
[The Coloration in Mammals and Birds. By J. Lewis Bonhote. 
Knowledge, vol. iii. 1905-6, pp. 293-294, 316-817, 343, 372-878, 402- 
404. | 
In ‘The Ibis’ for 1905 (p. 271) we noticed a paper by 
Mr. Bonhote on the Coloration of Animals, and we are 
now able to grasp his conceptions more completely from the 
fuller elaboration of his theories which les before us. He 
contends, as before, that coloration is due to physiological 
causes, and that in a high state of vigour we find a corre- 
sponding increase in pigmentation. Vigour itself is affected 
by two causes: (1) climate, including temperature and food- 
supply; (2) the rise and fall of sexual activity—the latter 
being the only factor practically worth consideration in 
tropical districts. Lack of colour would thus imply impaired 
vigour, and, in the case of the Polar Regions, only those 
animals which are able to retain full vigour would assume 
darker tints. The conditions of the Tropical Regions, on 
the other hand, lend themselves to a high state of vigour, 
and colours would be most pronounced there and less liable 
to change. Centres of bleaching, or “ pecilomeres,” are 
generally to be found, but are, for the most part, only 
noticeable during the growth of a new coat. 
29. Cooke on American Anatide. 
[Distribution and Migration of North-American Ducks, Geese, and 
Swans. By Wells W. Cooke. U.S. Dept. of Agricuit., Biol. Survey, 
Bull. 26. Washington, 1906. 90 pp.] 
The title of this pamphlet tells its own story, and we need 
