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Show 1886.] ON A BRACHIOPOD OF THE GENUS ATRETIA. 181 fact that the modification of the posterior air-sacs in Platalea was carried out on both sides of the body perhaps shows it to be a characteristic of the bird. Alimentary Canal.-The caeca of Chauna chavaria appear to differ slightly from those of Chauna derbiana, the most noticeable difference being that they are not symmetrical in the former species ; the right caecum is slightly longer than the left, and is of a uniform conical shape, tapering slightly to the free extremity ; it measured 3| inches from the tip to the junction with the ilium ; the left caecum measured as nearly as possible 3 inches. The left caecum also differs in its shape, as may be seen by an inspection of tbe accompanying drawing (p. 180); its proximal half is about equal in diameter to that of the right caecum, but instead of tapering gradually it narrows abruptly into the distal half, which is of about the thickness of the little finger. In the liver the right lobe is larger than the left lobe, and, as in the other species, there is a large gall-bladder the duct of which opens into the duodenum below the hepatic duct; the pancreatic duct is the most anterior of the three. Trachea.-The extrinsic muscles of the syrinx are somewhat differently disposed from those of Chauna derbiana ; as in that species, there are two pairs ; the most anterior spreads out in a fan-like manner upon a tough membrane which connects the coracoid and clavicle ; this muscle is therefore attached exactly as is its homologue in Ch. derbiana. The posterior pair of muscles are, however, not attached to the costal process of tbe sternum as in Ch. derbiana, but terminate upon the aponeurosis of the lung just behind the exit of the pulmonary vein. The syrinx itself does not appear to me to be worth a special description or figure, as it agrees in every particular with that of Ch. derbiana. 2. O n a Brachiopod of the Genus Atretia, named in M S . by the late Dr. T. Davidson. By Miss A G N E S C R A N E. (Communicated by Prof. W . H. Flower, LL.D., F.R.S.) [Eeceived March 15, 1886.] In July last the late Dr. Thomas Davidson, F.R.S., received from Mr. John Brazier, of Sydney, a gift of an interesting series of Brachiopoda dredged by him in the waters of Port Stephens and Port Jackson, New South Wales. When, in January 1886, it became my duty to select the remaining specimens from the Davidson collection necessary for the illustration of Parts 2 and 3 of Dr. Davidson's forthcoming Monograph on Recent Brachiopoda, these Australian specimens were not found incorporated with his collection of living species. Possibly it was Dr. Davidson's intention to describe them in a separate paper/ In February, when the collection of recent and fossil Brachiopoda (which, in accordance with Dr. Davidson's |
