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Show 1882.] ON THE ANATOMY OF ERETHIZON DORSATUS. 271 the possession of powder-down patches, in the oil-gland being nude (?Mesites), and in the interruption of the dorsal tract in the neighbourhood of the scapula?. Pterylographically, therefore, there is no special reason to unite these forms with the Rails. Judging from M . Milne- Edwards's account and figures of the osteology of Mesites, numerous differences between these two forms also exist in the osseous parts of their structure. In particular, the fact of Mesites being schi-zorhinal is a strong point in view of its relationship being, along with Rhinochetus aud its allies, to the Pluvialine group, where I have already - placed it. In spite of M . Milne-Edwards's remarks2, I see no reason for doubting the value of the schizorhinal character of the nasal bones as a mark of the genetic affinities of birds, especially when, as in the present case, other facts point in the same direction. I should be inclined therefore to consider (1) that Mesites, Eurypyga, and Rhinochetus have all sprung from some common ancestor,- which must have been a generalized Pluvialine form provided with powder-down tracts; (2) that of the forms which this common stock gave rise to, all have become extinct save the three in question, which, having become isolated in three widely separated localities, have each acquired certain special characters not found in the others ; (3) that, judging at least from the pterylosis, the Malagash Mesites is perhaps more nearly related to the New-Caledonian Rhinochetus than to the Neotropical Eurypyga. 5. Notes on the Anatomy of Erethizon dorsatus. By ST.-GEORGE MIVART. [Eeceived February 16, 1882.] Having had an opportunity, through the kindness of Dr. Giinther, of examining a spirit-specimen of Erethizon dorsatus, the following points have appeared to m e possibly of some interest. The tongue is long and narrow, its extreme length being 4"* 7 and its greatest breadth (at its hindmost end) being l"*4 ; close to the tip it is only'5 (cent.)3. Its hinder margin has a deep median notch. The intermolar eminence is considerable. There is no median groove on the dorsal surface ; and there are but two oval and rather large circumvallate papilla? at the hinder margin of the tongue. The long axes of these two papillae diverge forwards and outwards. The surface of the dorsum of the tongue is, for its anterior half, covered 1 Ibis, 1881, p. 4, and P. Z. S. 1881, p. 644. 2 The greater or lesser size of tbe beak will not account for the schizorhinal or bolorhinal character of the nares, as suggested by M . Milne-Edwards. Else why should tbe big-billed Platalece, Ibises, Bidwneulus, Larid@, Alcidce, be all schizorhinal, whilst tbe slender-billed Rails, Colymbida, and such Tubinares as Puffinus and Procellaria, to say notbing of such forms as the Meropidce, Dendro-colaptida, and Nectariniidm, are all equally holorhinal ? Nor can I admit witb M . Milne-Edwards that the Pteroclidat are related to the Gallincs, or the Ibididce to Tantalus, there being plenty of collateral evidence to prove the reverse. Hence any argument based on such assumed affinities also fails. 3 In this paper all the measurements are in centimetres, except where otherwise expressed. |
