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Show 538 MR. F. E. BEDDARD ON THE [Apr. 21 6. On the Anatomy of a Grebe (JEchmophorus major), with Remarks upon the Classification of some of the Schizognathous Birds. By FRANK E. BEDDARD, M.A., F.R.S., Prosector to the Society. [Received March 17, 1896.] As so few of the Grebes have been dissected, I took the opportunity offered, by the death some months since of a specimen of JEchmophorus major, to make some notes upon the principal viscera and muscles, which 1 n o w lay before the Society. As is well known, birds differ very much in the extent of a horizontal membrane which is attached laterally to the oblique septa and posteriorly and ventrally to the abdominal wall. This membrane has been Arariously termed " Omentum," " Pseuclepi-ploon," and " Horizontal septum." W h e n the abdominal viscera of the Grebe are exposed by cutting carefully through the body-wall at some distance behind the sternum, the cavity which contains them is seen to contain only the intestines. As is the case with many other birds, with many Passeres for instance, the duodenal loop is very extensive, reaching right to the end of the abdominal cavity. This cavity, containing the intestines, is shut off from the anterior part of the abdominal cavity by an almost vertical septum, which is the reduced equivalent of the horizontal septum. This septum cuts off from the intestinal cavity auother cavity which incloses the gizzard and the liver, and is again divided into right and left halves by the falciform ligament. The right cavity thus formed contains as usual only the right lobe of the liver. I should mention also, as a fact of some systematic importance, that neither tbe gizzard nor the entire extent of the liver is sheltered by the sternum; they lie nearly altogether behind it. In this particular AZchnophorus differs from Psophia, Cariama, and the Ballidae ; but the Grebe agrees with those birds as well as with the Ducks in the small extent of the horizontal septum. § Myologg. I have only made notes upon the more important muscles from a classificatory point of view. The arrangement of the tendons of the tensores patagii is characteristic. The tensor brevis is early divided into two separate tendons which run down the patagium to be inserted as usual on to the forearm. They do not, however, as in the majority of birds, form well-defined narrow tendons, but are thin and ill-defined sheets of tendon. The division which lies nearest to the humerus is particularly thin and difficult to delimit. The outer band has a thickened strand on the side nearest to the humerus ; it thins oft gradually on the outer side. The nerve to the hand passes under |