196 Herr. L. Zehntner on the Development of 



me and begin its melodious song, which much resembles that 

 of our Common Thrush, though inferior in volume. It is, 

 nevertheless, so varied and sweet, that the bird is fairly en- 

 titled to be called Hawaii's Nightingale. Mr. D. H. Hitch- 

 cock of Hilo told me that many years ago the natives used to 

 bring him the young of this species, which, for the sake of 

 their song, he kept in a cage. 



The habit of singing, like a Lark on the wing, possessed 

 by P. myadestina, as mentioned by Dr. Stejneger on Mr. 

 Knudsen's authority, was observed by me in both species ; 

 but the gentleman last named is incorrect in applying the 

 name of " Uapauau " or " Ou " to the one recently described. 

 The call-note of P. obscura is a particularly clear tweet, very 

 easily recognized, but it also utters a very remarkable hissing 

 sound when approached. Its flight is slow, and I have fre- 

 quently shot it as it was flying from tree to tree. It pos- 

 sesses also the very peculiar habit (not noticed by Mr. Knudsen 

 in regard to P. myadestina) of shaking its wings when 

 perched on a branch, as if it were shivering with cold or 

 seized with an attack of ague. 



The vertical range of this species extends from the lowest 

 forest-zone up to 5000 feet. 



XVII. — On the Development of the Feet o/Cypselus melba. 

 By L. Zehntner, Cand. Phil., of Bern."* 



Being at present engaged in a study of the development of 

 Cypse/us melba, especially directed towards the elucidation of 

 its osteological peculiarities, I publish the following inter- 

 esting results, reserving details for a forthcoming work. 



As is well known, the genus Cypselusis distinguished from 

 all others by the remarkable reductions in the feet. Accord- 

 ing to Huxley's law, we find in birds the first toe provided 

 with two, the second with three, the third with four, and the 



* Translated (by permission) from a paper in the ' Zoologischer An- 

 zeiger' (No. 319, 1889), entitled "Zur Entwiaklung von Cypselus melba 

 (Alpensegler)," von L. Zehntner, Cand. Phil, in Bern. 



