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Show 488 PROF. FLOWER ON THE DELPHINID.E. [Nov. 20, that group), where the lateral margins are nearly parallel, and the borders of the first three digits are in contact for nearly the whole of their length. In the conclusion of the description of this skeleton I said : - " If the osteological characters possessed by this specimen be found to exist in other Dolphins with narrow compressed beaks and long mandibular symphyses, Steno will be established as a natural group of generic value." The result has been quite otherwise ; for the skeleton described by Dr. Peters and that of the Chinese White Dolphin clearly belong to two different types. For the first the term Steno should be reserved. With what other known forms can D. sinensis be associated ? Since the publication of the description of its skeleton more information has been obtained regarding the animals of the group, properly distinguished by Gray as a special form, to which he gave the name of Sotalia, and the indications of the similarity of D. sinensis to D. guianensis, the type of the group, already pointed out, can be more completely developed1. Edward Van Beneden has given a very full description of the external and osteological characters of a specimen taken in the Bay of Rio, where it appears to be of very common occurrence. Unfortunately the individual upon which his description is based was an exceedingly young one ; and the imperfect development of the bones not only accounts for some of the peculiarities he noticed, but also renders a comparison with other specimens less satisfactory than it otherwise would be. Gervais has given figures and some details of the osteological characters of another species from the Amazon, D. pallidas ; and the British Museum possesses two skulls, also of very young individuals, obtained by Mr. Bates near Santarem, on the Upper Amazon, described by Dr. Gray under the name of Steno tucuxi. That these are all very closely allied forms there can be no question ; but the materials are not yet sufficient to work out their specific characters or geographical distribution. At present they have been found on the coast of Guiana, in the Bay of Rio, and in the upper waters of the Amazon. From the published descriptions it is very difficult to find any characters by which the Delphinus pal/idus of Gervais, Steno tucuxi of Gray, and Sotalia brasiliensis of E. Van Beneden can be distinguished specifically. To this group I have now no hesitation in adding Delphinus sinensis. It is curious that it agrees with the American form of which we have the fullest description (S. brasiliensis) in its pale coloration, and in its habit of frequenting estuaries and bays, and not the open sea. A cranium in the Museum of the College of Surgeons, found upon the sea-beach at Aripo, in the north of Ceylon, by Mr. E. W . H. Iloldsworth, closely resembles that of D. sinensis, but is of smaller size. Another animal apparently of the same group is Delphinus 1 See "Memoire sur un Dauphin nouveau de la Bale de Rio de Janeiro, Sotalia brasiliensis," by Ed. Van Beneden: Mem. de l'Acad. Roy. de Belgique, t. xii. 1874; and Gervais, in ' Osteographie des Cetaces,' p. 594. |