The young of Circus spilonotus and C. æruginosus are similar in plumage and as the size is also nearly the same it is a matter of some difficulty to distinguish between them. Sharpe identified as C. æruginosus a young female collected in the Philippines by Cuming, but he finally referred it to C. spilonotus. Whitehead obtained an immature male in northern Luzon which according to Grant "is undoubtedly referable to the present species [æruginosus]." Concerning the specimen from Calayan Sulu, collected by Mearns, Dr. Chas. W. Richmond writes that "it may prove to be spilonotus." Hartert makes no comment on the specimen collected by Everett in Mindoro. Some of the numerous brown marsh hawks in the Bureau of Science collection may be of this species but they can not be determined at present. Genus ASTUR Lacépède, 1799. Bill small and compressed, upper mandible with a deep notch or a strong sinuation near its tip; first primary short, third or fourth longest; tarsus rather long and with transverse plates in front and behind but the division lines between plates very obscure. Species. a1. Larger, length more than 330 mm.; under parts white, barred with brown or pale rufous. ... trivirgatus (p. 216) a2. Smaller; length less than 330 mm.; under parts not barred. b1. Breast light chestnut. ... soloensis (p. 217) b2. Breast light gray. ... cuculoides (p. 218) 176. ASTUR TRIVIRGATUS (Temminck). CRESTED GOSHAWK. Falco trivirgatus Temminck, Pl. Col. (1824), 1, pl. 303. Astur trivirgatus Sharpe, Cat. Birds Brit. Mus. (1874), 1, 105; Hand-List (1899), 1, 249; Oates, Cat. Birds' Eggs (1902), 2, 243; McGregor and Worcester, Hand-List (1906), 41. Balabac (Everett); Leyte (Everett); Mindanao (Everett, Steere Exp., Platen, Bourns & Worcester, Celestino, Goodfellow); Palawan (Whitehead, Platen); Samar (Bourns & Worcester, Whitehead). Indian Peninsula, Indo-Malayan Islands, Ceylon, Formosa.