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Show 152 MR. F. E. BEDDARD ON THE SYRINX AND OTHER [Mar. 2, and anterior air-sacs ; towards the median line, however, its limiting septa coalesce, and here the anterior and posterior intermediate air-sacs follow each other directly; this supplementary air-sac therefore is placed upon the outer margin of the lung and does not extend to the middle line. The other specimen of Steatornis unfortunately had the lungs destroyed, so that I cannot positively state whether the above-described peculiarity is merely a variation or characteristic of the bird, though on one side there' were certainly two ostia to the posterior intermediate sac. Myology. The disposition of the tensores patagii varies characteristically in the different genera. In Caprimulgus, Nyctidromus, and Chordeiles there is a biceps-slip, which is absent in Steatornis, Podargus, and Mgotheles. Prof. Garrod has figured the patagial muscles of Steatornis (loc. cit.), and I find them to be exactly similar in Podargus. AiJgotheles is a little different from either of these genera ; there is no anterior branch to the tendon, or only just a trace of one, close to the insertion on to the extensor muscle. In Caprimulgus, Chordeiles, and Nyctidromus there is an absolute similarity in respect of these muscles; since Caprimulgus has been already figured by Garrod (loc. cit. p. 185), there is no necessity to illustrate the two remaining genera, as it would be merely a repetition of his figure. A peculiarity in the myology of Steatornis is not referred to by Prof. Garrod in his account of the anatomy of that species; that is the presence of an expansor secundariorum. In a later paper, where a list is given of those families that are characterized by having an expansor secundariorum muscle, he states that the Coraciidae are the only Anomalogonatous birds which are thus provided. In the specimen of Steatornis before me there is a well-developed expansor secundariorum arising in the usual way and attached to the teres near to its insertion. The termination of the expansor secundariorum in Steatornis is therefore similar to that which has been recorded by Garrod in Ortyx, Numida, &c. Since noting this fact I see that Mr. Forbes1 has already mentioned it. The biceps muscle is split about halfway down into two distinct tendons of insertion, which are severally attached to the radius and ulna. In Podargus, A^gotheles, and Nyctidromus the biceps is similarly divided into two, the division passing for a certain distance into the substance of the muscle itself, and not being merely restricted to its tendon of attachment. This structural feature is not peculiar to the Caprimulgidae, but is found in other families of birds. In all the raprhnulgidae that I have dissected, the anconeus longus has a tendinous humeral head. The peroneal muscles vary in the different genera of Caprimulgidae : in Steatornis and AZgotheles only the peroneus brevis is present; in Podargus both peroneals are present with the usual attachments ; in Nyctidromus I could only find the peroneus longus. Coll. Papers, p. 346. |