Page:Bird-lore Vol 01.djvu/234

 Bird- Lore CROSSBILL AND HORNED LARK small birds whose diet consists largely of insects. Strictly insectiv- orous birds, such as Swifts, Swallows and Goatsuckers, have a some- what different tongue, — soft, fleshy, and beset, particularly about the base, with numerous small backwardly directed points, whose office is apparently to facilitate the downward career of food. That these birds, so different in structure, as birds go, and members of families so far apart in the bird world, should have similar tongues, seems to indicate that the shape of the tongue bears a relation to the character of the food, and gives no hint of correspond- ing relationship between the birds themselves. The more exclusively granivorous birds have another style of tongue, — smooth, thick, fleshy and but little frayed at the tip, — a tongue which no doubt is useful for hold- ing and husking minute seeds, while the little scoop-like tongues of Goldfinches and Crossbills must be still more serviceable for such purposes. The tongue of our common Goldfinch is furthermore beset about its edge with little hard points, and while these would add to its usefulness in gathering the fine seeds of thistles, yet, as thistles are only available for a part of the year, it is hardly probable that such a special modification is for such limited use, this being one of the cases where it is easier to make the theory fit part of the THE LITTLE facts than it is to make the facts conform to the theory, ^GotD?rNCH^ My friend Mr. William Palmer has, however, offered a suggestion that seems to fit the case pretty well, calling attention to the fine, almost pasty condition of food found in the gullet of the Goldfinch, and suggesting that the small, hard points play a part in grinding up little seeds and reducing them to pulp. If we go back to the simple tongue with which we started, stretch it out and feather it more deeply, we will have the pattern of tongue that prevails among the Orioles ; or if we curve the thin edges upwards and inwards until they meet, we will have a little tube, such as is found among the Sunbirds and Honey-suckers. In order that such a tongue may really suck, it is, of course, nec- essary to create a vacuum at its back, and the muscles of the tongue are so arranged that this can be done, the back of the tongue being depressed, while the front or middle portion is in contact with the roof of the mouth. Some of the American Honey-creepers {Ccvreba), for example, have an interesting modification of this suctorial tongue, the front portion being deeply cleft and the thin edges split and rolled inward to form two hollow brushes. These may either dip up liquid, or draw it inward by capillary attraction, while they are