THE BIEDS OF AUSTRALIA. 
for 8. anglica. After careful consideration, if generic names are used for these 
Terns, the correct usage must be : — 
Thalasseus Boie, 1822 . . . . . . Type T. sandvicensis. 
Hydroprogne Kaup, 1829 . . . . Type H. tschegrava. 
Gelochelidon Brehm, 1831 . . . . Type G. nilotica. 
The action of Kaup in introducing Actochelidon for 8. cantiaca cannot be 
claimed as invalidating Brehm’ s almost simultaneous splitting of Boie’s genus. 
If such be accepted, scarcely any of the presently-accepted genera will stand 
the test, and much confusion would result without the serving of any good 
purpose. As a matter of fact the type-designation by Gray, 1840, could not 
be abrogated on account of Kaup’s separation of 8. cantiaca as type of a 
monotypic genus previously, as by means of that argument Gray’s selection 
of 8. caspia type in 1855 was doubly invalid : 8. caspia was the mono- 
typic type of 8ylochelidon Brehm, 1831, and had previously, in 1846, been 
designated as type of Hydroprogne Kaup, 1829, by Gray himself, as well as 
being the monotypic type of Helopus Wagler, 1832. 
It might be noticed here that in the A.O.U. Checklist, 3rd ed., p. 42, 
1910, the prime entry of Gelochelidon is given as : — 
“ Gelochelidon Brehm, Isis, XXIII., 1830, p. 994. Type, by monotypy, 
Lachseeschwalhe, Gelochelidon ineridionalis Brehm = 8terna nilotica Linnaeus.” 
I beheve the entry I have selected at the beginning of this article to be the 
correct one, as Brehm, at the place quoted {Isis, 1830) only indicates the species 
by means of vernaculars and nude Latin names, the descriptions not being 
offered until afterwards. In this case Brehm had previously named a 8terna 
meridionalis, but that is no reason for accepting Brehm’s name, as Brehm used 
the same specific name so commonly in closely-aUied groups. 
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