Page:The birds of America, volume 7.djvu/315

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WILSON'S PETREL.
227


along the edge of lower mandible y^; tarsus If; middle toe 1, its claw T ^. Weight l-§- oz.

Adult Female.

The female resembles the male.

The palate is marked behind with four longitudinal ridges, which are papillate, and before with three ridges; the mouth A twelfths in width, but capable of being dilated to 9 twelfths; the tongue inch long, triangular and acuminate, at the base concave and emarginate, fiat above, with a slight median groove. The lobes of the liver are equal, their length 7^- twelfths. The oesophagus, a b, has a uniform width of 3 twelfths until it enters the thorax, when it at once expands into an immense ovate sac, b c de, 1 inch 11 twelfths long, viewed ante- riorly 1 inch 1 twelfth in breadth, laterally 1 inch 2 twelfths. This sac is formed, pro- perly speaking, of the proventriculus; its walls are extremely thin and transparent, and it is studded all over with roundish glandules placed at a considerable distance A from each other. It curves upwards in front, and becomes narrowed to 2 twelfths, ending in the stomach, which is an extremely di- minutive gizzard, of an oval form, only 3j twelfths long, and 3 twelfths in breadth. The stomach is thus reversed in position, its

fundus being anterior; and accordingly the intestine,/^ h i, comes off from its left instead of its right side, forms a semicircular sweep round the fundus, then passes backward for 1 inch, to f, bends forward to the liver, at g, and forms a number of loops, g h i, making in all 9 turns. The duodenum is 1 inch | twelfth wide, and the intestine continues so for half its length, when it gradually contracts to f twelfth, and is rather less in the rectum, which is terminated by a very small globular cloaca, j, 3^ twelfths in diameter. There are no cceca. The intestine measures 14 inches. The stomach pro- perly so called is lined by a rugous epithelium, and is in fact a true gizzard. It contains a quantity of shell-sand. The inner surface of the proventriculus is soft and smooth; that of the oesophagus longitudinally plicate. The trachea is 1^- inches long, from twelfths to 1 twelfth in breadth, flattened, with rings 84 in number, slender, and unossified. Bronchi wide, of 25 half rings.