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Show 1877.] MR. A. H. G A R R O D O N T H I N O C O R U S A N D ATTAGIS. 417 therefore considered certain, notwithstanding the partial resemblance of their vomers. Next with reference to Chionis. By De Blainville this genus has been located close to Hcematopus1; and his view has been accepted, to a greater or less extent, by many. Nevertheless, although these birds are both strictly schizorhinal, their skulls give indications of a very different affinity. Hcematopus possesses supraoccipital foramina, as well as pterygoid articulations with the basisphenoid, together with a bifid vomer, as represented in fig. 2. The similarly formed vomer is extraordinarily broad in Recurvirostra avocetta, which is shown in Ilii Anterior extremity of vomer in:-1. Sterna hirundo; 2. Hcematopus ostralegus; 3. Numenius arquatus; 4. Recurvirostra avocetta ; 5. Chionis alba. fig. 4, agreeing with the restricted Limicolse; whilst in Chionis the vomer is blunt (fig. 5), and the basisphenoid rostrum, as well as the pterygoids, are entirely free as far as articulating facets are concerned. In the Bulletin of the United States National Museum2 Dr. E. Coues and Mr. Kidder, after a most careful study of the whole anatomy of the genus, Chionis minor especially, remark, " W e find in Chionis a connecting link, closing the narrow gap between the plovers and gulls of the present day. In our opinion this group represents the survivors of an ancestral type from which both gulls and plovers have descended"3. A separate division, termed Chio-nomorphse, is established for them, comparable with the Gerano-morphae and the Cecomorphse of Prof. Huxley4. M y dissections of both C. alba and C. minor are quite in favour of this Larine affinity. That the genus deserves to be located in a separate division, however, as Dr. Coues suggests, I cannot agree. The Cecomorphse of Prof. Huxley include the Laridse, Procellariidse, Colymbidse, and Alcidse; and it is now known that neither the Procellariidae nor Co-lymbidae come near the Laridse and Alcidse, which two last-named families are related one to the other most intimately, and differ from one another to almost exactly the same amount as the Chionididse do from either. I should place the Chionididae, the Laridse, and Alcidse 1 Annales des Sciences Naturelles, vi. 1836, p. 97. 2 No. 3, p. 85, Washington, 1876. * L. c. p. 114. * P.Z.S. 1867, p. 457. PROC. ZOOL. SOC-1877, No. XXVII. 27 |