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Show 1903.] OSTEOLOGY OF THE CUCULIFORMES. 287 but the latter at any rate is the direct outcome of adaptation. Probably the remarkably specialised condition of the pelvis also is adaptive. In the accompanying table it will be found that I have arranged the Cuckoos on a plan formed of a compromise between that of Beddard, based on the pterylography and voice-muscles, and one based on the osteology and voice-muscles. The two will be found to disagree in many points; and it is on this account that I have published the results of my comparison, since it will, I hope, stimulate further research by directing renewed attention to the anatomy of the discordant forms. A. Sternum with single pair of notches ; pectineal process of pelvis vestigial. Muscle-formula A X Y -f-, except 1Eudynamys which has the formula A B X Y + . Cuculus. Coccystes. Coccygus. Eudynamys. Scythrops. b. Syrinx bronchial. , „ , 7 Muscle-formula A B X Y + . j Crotophaga. W r t v ^ ( Quvra. a. Syrinx traclieo-broncliial. Muscle-formula AXY-J-, except Eudynamys which has A B X Y 4- • ' Old World. New World. B. Sternum with single pair of notches; pectineal process of pelvis large. c. Syrinx bronchial. . Muscle-formula A B X Y + . ( Centropus. Old World. <• dromococcyx. C. Sternum with two pairs of notches ; pectineal process large. d. Syrinx bronchial. Muscle-formula A B X Y 4-. New World ............................................. Geococcyx. Old World ............................................ Coua. Syrinx tracheo-bronchial. Muscle-formula A B X Y + , except Piaya which has A X Y -K Old World. Rhinococcyx. Rhamphococcyx. Urococcyx. Rhopodytes. Zanclostomus. Taccocoua. Piaya. (New World.) D. Sternum with two pairs of notches; pectineal process vestigial. f. Syrinx tracheo-bronchial. ^ Muscle-formula A X Y 4*. \ Clrysococcyx. Old World. <• Cacomantis. Mr. Beddard has shown, in tabular form, the points wherein the skulls of the Cuculi and Musophagi differ one from another. These are not many, and I cannot but think that they are really of slight importance. The most striking are the differences in the size of the antorbital plate, the position of the maxillary end of the quadrato-jugal bar relatively to the tomium, and the relation of the mesial borders of the proximal ends of the palatines. The desmognathism of the palate seems to me to be precisely similar in both forms. If the skull of Turacus, for example, be compared with that of Coua, it will be found that the chief difference lies in the more spongy nasal septum of the latter, P roc. Z ool. Soc.- 1903, V ol. I. No. X IX . 19 |