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Show 742 MR. COLLETT ON THE SKULL OF STRIX TENGMALMI. [Dec. 5, below the middle. In Strix otus and S. brachyotus, however, it is almost entire and without any incision. But in S. tengmalmi there appears the peculiar extension, already mentioned, which reaches ID front of the ear-openings and bends downwards and finally inwards. This process in the ' crista' proves to be only asymmetrical in appearance, extending on the one side (where it is itself shorter than on the other) far more downwards than on the opposite side. On close examination it will be found that this process projects on both sides to an equal distance from the upper end of the ' crista;' and having the same length and curvature on each side, it consequently terminates higher up on the riyht side (where, as has been said, the ' crista' is longer) than on the left (where the ' crista' is shorter). The apparent asymmetry of this process is therefore not due to its own structure, but to the ' crista' itself. While this extension of the right prolonged 'crista' bends forwards, downwards, and finally inwards, above the ' os jugulare,' and touches with its rounded extremity the lowest and outer edge of the ' processus orbitalis posterior,' it bends on the left side (which is shortened) beneath the 'os jugulare ' and widens at its extremity into an oblong ' condylus,' which fits into and articulates (sometimes feebly but yet plainly) with a corresponding surface on the * os coro-noideum maxillae inferioris,' jointly with the normal 'os quadratum ' and ' os jugulare.' The ' cranium ' in this way comes into immediate contact with the lower jaw (as seen in fig. 4, p. 740). As to the other parts of the ' os squamosum,' it may be said that the ' processus zygomaticus ' is but very feebly developed. The 'processus orbitalis posterior' seems in this species (as appears also to be the case in young examples of Strix aluco) to be formed solely of the ' os alisphenoideum ;' but, as in all the Strigidce, it is very strongly developed, forming a considerable part of the outer side-wall of the orbit, and bending down, like a flattened sharp-ending nail, before the ' os squamosum,' without (as is the case in S. flammed) reaching the 'os jugulare.' The precise nature and extent of any asymmetry in the other bones, coalescent with the ' os squamosum,' I am not at present able to point out. That there must be a modification in a slighter degree of the ' os alisphenoideum,' ' os frontale,' and 'os parietale' (especially of the last) is perfectly consequent, and it strikes the eye on a cursory examination of the skull. But for this purpose examples of younger individuals, which I have not yet obtained, are required. An examination of an immature example preserved in the Museum of the University of Christiania, the plumage of which is minutely described in the ' Nyt Magazin for Naturvidenskaberne' (xviii. p. 161), led to no result, the cranium (on account of its youth) being defective. The observations above recorded are based on an examination of nearly a dozen skulls of Strix tengmalmi, all of which have proved to be alike even to the most minute particulars. P.S.-Doubtless the nearly allied (if, indeed, specifically distinct) |