OCR Text |
Show 534 MR. GARROD ON THE ANATOMY OF STEATORNIS. [June 3, in the Strigidae, whilst in the Caprimulgidae it is more developed, reaching the lower margin of that bone. The tensor patagii brevis-a muscle very constant in its insertion in the different families of birds, which arises mainly from the superior extremity of the furcula on each side, and is inserted, after running in the patagial fold parallel to the humerus, into the outside of the forearm near the elbow-in Steatornis agrees entirely with that of many of the Strigidae, and differs slightly from that of the Caprimulgidae, as may be seen from the accompanying drawings (fig. 4, p. 533), where, in the former, the main tendon becomes attached to the extensor carpi radialis longus directly, whilst in the latter it joins a second more superficial tendinous slip which runs back to the outside of the elbow, much as in the Passeres. By placing the above-mentioned facts in a tabular form, the comparison between Steatornis and its allies will be more clearly seen. Number of carotids Semitendinosus muscle ... Femoro-caudal muscle ... Pectoralis secundus muscle Steatornis. 2 Present, with accessory head. Short Strigidee. 2 Absent Present (small) Short Caprimulgidce. 2 Absent. Present, with accessory head. Present. Long. The semitendinosus is a muscle very constantly present iu birds, being absent only in the Owls, Eagles, true Vultures, Hummingbirds, and Swifts ; consequently its presence in Steatornis is in favour of its being related to the Caprimulgidae rather than to the Strigidae. In endeavouring, from the facts recorded above, to form a correct notion as to the exact systematic position of Steatornis, the difficulties in the way are considerable. That it forms a family by itself there is little or no doubt, as it presents pterylographical and internal peculiarities found in no other birds. By a process of exclusion, an approximate idea of its position may be formed. The Strigidae, Caprimulgidae, Coraciidae, Momotidae, Galbulidae, and Steatorni-thidae all agree in possessing the following characters-two carotids, well-developed caeca, a nude oil-gland, and no ambiens muscle. Among these, the Strigidae differ from all the rest and resemble the Eagles, in having no semitendinosus; and the Steatornithidae are equally peculiar in having no femoro-caudal muscle. In its pterylosis, as shown above, Steatornis resembles the Strigidae much more than any of the allied families, except that there are only ten rectrices. I have not dissected Podargus ; but it agrees so closely with Caprimulgus in its pterylosis, according to Nitzsch, that it most probably must be included in the same family. As Mr. Sclater has shown, Podargus has no oil-gland, that organ being very small in the Caprimulgidae generally, but large in Steatornis. If the absence of the ambiens muscle in the Strigidae has the significance which I put on it, and is sufficient justification, in |