The structure and classification of birds (1898) (14746387351)

Identifier: structureclassif00bedd (find matches)

Title: The structure and classification of birds

Year: 1898 (1890s)

Authors: Beddard, Frank E. (Frank Evers), 1858-1925

Subjects: Birds -- Anatomy Birds

Publisher: London New York (etc.) Longmans, Green, and co.

Contributing Library: MBLWHOI Library

Digitizing Sponsor: MBLWHOI Library

Text Appearing Before Image:

e orabsence of the after shaft appears tobe of little use for systematic pur-poses. Among the ducks, for ex-ample, some have it and some haveit not. It is as large as the mainfeather in the emus and totallyabsent in Rhea. Facts like these,which might be multiplied, throwdoubts upon the value of thisstructure in classification. So toowith the oil gland and its feather-ing or absence of a tuft. Cancroma,which in other points of its structure conforms to the herontype, is alone in that group in having a nude oil gland. Thegland is absent in some parrots, present in others. GAERODat one time thought that he could correlate among thePico-Passeres a nude oil gland with small caeca, and a tuftedoil gland with the absence of ca3ca ; to the vast majorityof picarian birds there is no doubt that the correlation does 1 A. PILLIET, Sur la Glande Sebacee des Oiseaux, &c., Bull. Soc. Zool. Fr.xiv. 1889, p. 115 • E. KOSSMANX, Ueber Talgdriisen der Viigel, ZeitscJn: f.iriss. Zool. 1871, p. 5lis.

Text Appearing After Image:

FIG. 4.—FEATHEK SHOWING AFTEESHAFT (AFTER SCLATEB). PTERYLOSIS 19 apply. But the todies were found to be birds with a tuftedoil gland and with large caeca. It has been pointed out that when the oil gland has atuft of feathers upon its apex the rest of the gland is un-feathered, and that, on the contrary, when the tip is nudethe general surface of the gland is feathered. The oil glandis, so far as we know, a structure special to birds ; it is, indeed,the only purely external glandular apparatus that exists inthem. It is therefore possible, if not probable, that theorgan first arose in the class—that it is not an inheritancefrom any ancestor. On this view it is quite possible thatthe absence of the oil gland may not be always due to itsdisappearance; birds without oil glands may or may nothave lost them. It seems very likely, for example, that theusual absence of this structure among the struthious birdsis rather a primitive than a secondary character. If thisview of the matter is j

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1898

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