136 
L ARID.1C. 
Genus HYDROPROGNE Kaup. 
Hydroprogne Kaup, Skizz. Entwick.-Gesch. Nat. Syst. p. 01 (pref. 
April), 1829. Type (by subsequent designation, Gray, Gen. 
Birds, vol. iii. p. 558, 1816): Sterna caspia Pallas. 
Sylochelidon Brehm, Vogel Deutschl. p. 767 (pref. July), 1831. Type (by 
monotypy): 8. balthica Brehm — 8. caspia Pallas. 
Helopus, Wagler, Isis, 1832, heft xi. col. 1224, Nov. Type (by monotypy): 
S. caspia Pallas. 
Pontachelidoti Hogg, Edinb. New Philos. Journ. vol. xli. p. 69, 1846. Type (by 
subseqnent designation, Mathews, Austral Av. Bee. vol. ii. p. 133, 1915): 
8. caspia Pallas. 
Heroproyne Buller, Suppl. Birds New Zeal. vol. i. p. 157, 1905: error only. 
Hydroprogne caspia (Pallas). 
Distr. —Europe, Asia, North America, and south to Australia 
and New Zealand. 
Hydroprogne caspia, caspia (Pallas). (25-32.) 
Sterna caspia Pallas, Nov. Comm. Acad. Sci. Petrop. vol. xiv. p. 582, 
1770: Caspian Sea. (Fig. Dresser, viii. pi. 584.) 
Distr .—Europe and Asia. Extra-limital.] 
Hydroprogne caspia strenua (Gould). 
Sylochelidon strenuus Gould, Birds Austr. pt. xxii., March 1st, 
1846: Port Stephens, New South Wales, error = Tasmania. 
(Fig. Gould, Austr. vii. pi. 22; Math. ii. pi. 105.) 
Distr* —Southern Australia. 
Hydroprogne caspia yorki Mathews. 
Hydroprogne tschegrava yorki Mathews, Austral Av. Bee. vol. ii. 
p. 125, Jan. 28tli, 1915 : Cape York, Queensland. 
Distr. —Northern AustraIia. 
Hydroprogne caspia oliveri M. & I. 
Hydroprogne tschegrava oliveri Mathews Sc Iredale, Ibis, p. 242, 
April 1913: New Zealand. 
Distr . —New Zealand. 
Genus THALASSEUS Boie. 
Thalasseus Boie, Isis, May 1822, heft v. col. 563. Typo (by subsequent 
designation, Gray, p. 79, 1840) : S. cantiaca Gmelin = S. sand- 
vicensis Latham. 
Actochelidon Kaup, Skizz. Entwick.-Gesch. Nat. Syst. p. 31 (pref. April), 1829. 
Type (by monotypy): S. cantiaca Gmelin=6\ sandvicensis Latham. 
Pelecaiwpm Wagler, Isis, 1832, heft 3, col. 277, March. Type (by monotypy): 
Sterna pelecanoides King. 
