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Show 1876.] MR. DRESSER ON THE BLACK AND HAZEL GROUSE. 345 li inch high, covered at its blind end with the crypts of shallow glands, which also run down its sides. That it is a modification of the bursa Fabricii cannot be doubted. EXPLANATION OF THE PLATES. PLATE XXVI. Pig. 1. View of left side of neck of Plotus anhinga, dissected. I.e.a. longus colli anterior muscle ; I.c.p. longus colli posterior muscle. The fibrous representative of Donitz's bridge is seen attached to the ninth cervical vertebra. 2. View of part of tbe posterior region of the neck of Plotus anhinga. Tbe roman figures refer to the cervical vertebrae counted from the head. Donitz's bridge is seen attached to tbe ninth; and at a is also seen a fibrous band, which is of similar function, attached to the eleventh. At b is seen the fasciculus of the tendon of the posterior neck-muscle which traverses the fibrous loop, which latter has been removed on the left side. PLATE XXVII. View of the anterior thoracic region of Plotus anhinga, dissected to show the superficial (p. 1, 1) and deep layer (p. 1, 2) of the pectoralis major muscle on the right side, as well ;*s the pectoralis minor (p. 2) on the left. The insertion of the deeper layer of the pectoralis major is seen to be surrounded by the much more considerable mass of the similar portion of the superficial stronger layer. The triceps (t) and the biceps (b) of the cubitus are seen on the right side, as is the patagial slip (b. s) of the latter. The sternum (st.) is superficially bound to the lower end of the coracoid bone by the anterior sterno-coracoid ligament (ant. st. cor. lig), which is particularly powerful in the Steganopods and Storks. PLATE XXVIII. Fig. 1. View of top of head of Plotus anhinga, showing the occipital style (a) and the temporal muscle (t) arising from it on one side. 2. Stomach of Plotus anhinga, inside view. 3. Anterior view of the lower end of the trachea in Plotus anhinga. 4. The same in Sula bassana. 5 & 6. Top and side view of the patella in Phalacrocorax carbo, showing the canal for the ambiens muscle. N.B. The side view (fig. 6) is accidentally drawn with the base uppermost. 7. Front of patella in Plotus anhinga deeply grooved by ambiens muscle. 2. Remarks on a Hybrid between tbe Black Grouse and the Hazel Grouse. By H. E. DRESSER, F.Z.S. Amongst the Gallinaceous birds, and especially amongst the Ducks, we not unfrequently find wild hybrids; and not a few of these hybrids have during the last year or two been exhibited at the meetings of this Society-but none, I may almost venture to say, so interesting as tbe bird I have now the pleasure to exhibit before the meeting; for there can be no doubt that it is a wild cross between the Black Grouse (Tetrao tetrix) and the Hazel Grouse (Bonasa betulina), a cross that has, so far as I can ascertain, never yet been recorded. The Backelvogel of the Swedes, the hybrid between the Capercailly and the Black Grouse, is by no means uncommon, especially*in places where the males of the Capercailly have been |
