1873.] THE SECRETARY ON ADDITIONS TO THE MENAGERIE. 433 



only, but is possessed in common by both. Its origin, therefore, 

 may not be traceable directly to "sexual selection ;" still it may be 

 that an attractive peculiarity in one sex has subsequently been 

 adopted as equally attractive by the other, and hence the habit of 

 nibbling their tail-feathers universally practised by both sexes alike. 

 Anyhow we seem in this instance to be brought into nearer view of 

 the origin of this peculiar feature than is attainable in most other 

 instances of the kind ; and we also see certainly a method by which 

 similar racket-shaped tail-feathers, originating in the voluntary act 

 of the bird and fostered by sexual selection, might be produced in 

 one sex or both in a permanent form. In other birds, such as Ste- 

 ganura, Loddigesia, and Discura, amongst Humming-birds, similar 

 features prevail, and also in such cases as Prioniturus amongst 

 Parrots, and Tanysiptera amongst Kingfishers ; but in both of these 

 last, as in the Motmots, the character is common to both sexes. 



Referring to Steganura, we have a specimen of S. underwoodi 

 showing that the rhachis of the tail-feathers (in this case the lateral 

 ones) is clean from the first. Here the process of nibbling the 

 webs may have been carried on till the character has become natural 

 by the gradual weakening of the development of the webs attacked 

 until they were finally eliminated. In Steganura cissura, however, 

 the lateral feathers are simply narrowed. This may have arisen from 

 the abandonment of the habit by this particular species after it com- 

 menced segregation from the primitive stock of Steganura, that 

 stock, as in Momotus, not having then acquired the racket tail- 

 feathers in a permanent form. 



Whether the same cause has produced the racket-shaped tails in 

 Prioniturus and Tanysiptera is more difficult to trace, as it would 

 appear that in these birds the rhachis becomes more and more denuded 

 in each successive moult, showing other causes at work. On the 

 origin of such highly complicated structures as the tails and other 

 features of some of the Paradiseidse the present supposition throws 

 no light. 



May 6, 1873. 

 . Prof. Newton, F.R.S., V.P., in the Chair. 



The Secretary read the following report on the additions to the 

 Society's Menagerie during the months of March aud April 1873 : — 



The total number of registered additions to the Society's Mena- 

 gerie during the month of March 1873 was 68, of which 5 were by 

 birth, 16 by presentation, 41 by purchase, 1 by exchange, and 5 

 were received on deposit. The total number of departures during 

 the same period by death and removals was 85. 



The most noticeable additions during the month of March were 

 as follows : — 



1. A second specimen of the Western Ground-Parrakeet of 

 Australia (Geopsittacus occidentalis, Gould, Suppl. B. of Austr. 



Proc. Zool. Soc— 1873, No. XXVIII. 28 



