342 Recently j^uhlished Ornithological Works. 
58. Hartert on an overlooked Swift. 
[On an overlooked Indian Swift, By Ernst Hartert. Omis, xi. p. 199.] 
The resuscitated Swift is Cypselus acuiicauda of Jerdon 
(B. Ind.^Suppl. p. 870, 1864), which in the B. M. Catalogue 
(xvi. p. 444) has been united to Micropus apus pekinensis. 
Mr. Hartert has now found a second specimen in the Tring 
Museum (from Cherripungi, Khasia Hills), which he has 
compared with the type in the Liverpool Museum (from 
Nepal) and found to be identical with it. He calls it Apus 
acuticauda, and describes its characters. We prefer to call 
it by Blyth's name Cypselus acuticauda. 
54. Hartert and Hellmayr on two new Thrushes. 
[On two new Thrushes from Western Colombia. By Ernst Hartert 
and Carl E. Hellmayr. Nov. Zool. viii. pp. 492, 493.] 
Turdus ignobilis goodfellowi, from the Cauca valley of 
Colombia, and T. colombianus (a southern representative of 
T. obsoletus, but nearly allied to T. nigrirostris), from Cali, 
Western Colombia, are described as new. 
55. Helm on some Birds of Heligoland. 
[Ueber einige ornithologische Beobachtungen auf Helgoland. Von F. 
Helm. Ornithol. Monatsb. ix. pp. 149-151.] 
This paper treats of the Starling, Linnet, Swift, Hooded 
Crow and Wild Duck, as noticed on Heligoland. 
56. Helm on the Flight of Birds, 
[Betrachtungen tiber die Beweise Gatke's fiir die Hohe und Schnel- 
ligkeit des Wanderflages der Vogel. Von F. Helm. J. f. 0. 1900 
pp. 436-452. " * ' ' 
Weitere Betrachtungen iiber die Beweise Gatke's fiir die Hohe und 
Schnelligkeit des Wanderfluges der Vogel. Von F. Helm. J. f. 1901 
pp. 289-303.] ' ' • f 
Herr Helm considers that, although we may agree with 
many of Gatke's statements regarding the flight of Birds, 
certain of his conclusions are most surprising, and are founded 
on premisses which may be shown to be false. Especially 
