OCR Text |
Show 386 MR. W. A. FORBES ON T H E [May 4, linear process, formed only by the right half of the last tracheal ring, which is thus like the antepenultimate, incomplete for a part of its course. The first bronchial semirings are much thickened and strongly arched: they are nearly in contact in front in the middle line, and are separated by but a narrow space from the last tracheal ring; behind they become incurved and thickened. The second bronchial semiring is the slenderest of all; it is shorter than the first or third, and slightly concave downwards. There is the same pseudo-ring formed, apparently by accumulation of tissue inside, between it and the first semiring as already described in Euryleemus, but it is not so apparent here. The third semiring is much longer, being the longest of all the semirings, and in consequence projecting at both extremities. It is nearly straight, narrow, but not so narrow as the second ring, dilated behind and tapering slightly towards the front. The first, second, and third semirings of each side are nearly in contact with each other before and behind. The fourth ring has much the same shape as the third, but is slightly shorter, and more concave upwards than that one. The intervals between the second and third and third and fourth rings are somewhat deeper than are the rings themselves. The fifth and succeeding rings take on the usual form of bronchial semirings, gradually becoming more complete. As in Euryleemus, the single intrinsic tracheal muscle, which is very slender, is inserted slightly behind the middle of the first bronchial semiring. The Eurylcemidee are therefore, as is evident from this description, Mesomyodian1, in that respect agreeing with most of the other " Formicarioid" Passeres of Wallace (Ibis, 1874, p. 406). It is probable that the existence of an intrinsic muscle in the syrinx of Cory don sumatranus escaped the notice of Johannes Miiller-always supposing that in that species the same essential form of syrinx occurs as in those above described-owing to its slenderness. They are not Tracheophone; and in that they possess the sciatic, instead of the femoral artery2, they differ from the Pipridce and Cotingidee, with which the}* have so often been associated. From these, too, they differ, as they do from the Tyrannidce, Pittidee, and Rupicola, in the details of their syrinx as well as in the simple manubrium sterni and other points. As has already been stated, they differ from all the other Passeres in the retention of a vinculum in the deep flexor tendons of the foot. To the general bearing of these facts on the classification of the Passeres, I hope to return on some future occasion. 1 Garrod, P. Z. S. 1876, p. 517- 8 Cf. Garrod, P. Z. S. 1876, p. 516. |