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Show 1883.] PROF, F L O W E R O N THF. DELPHINID^E. 485 very wrell-marked species are common in every museum1, there is, so far as I am aware, no skeleton or any part of a skeleton which certainly belongs to it preserved anywhere, and very few of the skulls have localities assigned to them. In the Leiden Museum two are said to he from the " Indian Ocean " and one from the " Atlantic ;" Indian Ocean, Red Sea, and the Pacific are the localities given by Dr. Gray; while Van Breda's specimen, supposed to belong to this species, and from which alone its external characters are known, came from the coast of Holland. It does not appear to have been met with hitherto in the seas around New Zealand or Australia, or in the North Pacific. Among the skulls of this form of Dolphin are two well-marked varieties, distinguished by the amount of lateral compression of the rostrum. To the broader form the name of rostratus is more properly applied : while those (otherwise quite similar) with a very compressed rostrum have been specifically distinguished by Gray under the name of Steno compressus (Erebus and Terror, p. 43, tab. 27, 1846). Specimens of this form from the Indian archipelago were, however, previously described by Schlegel (Abhandl. p. 27, Taf. iii. figs. 2 & 3, 1841) as Delphinus reinwardtii, which name will therefore have the priority if it should prove to be a good species. In the series of ten skulls in the British Museum the two extreme forms look very distinct, but others are quite intermediate ; and when the whole series is placed together in order such a regular gradation can be traced, that it becomes impossible to say where the broad form ends and the narrow one begins. Dr. Gray evidently met with this difficulty, as the names attached to the skulls show; some which are marked by him S. compressus being indistinguishable from others labelled S.frontatus. In the series at Leiden exactly the same occurs, the two forms passing insensibly into each other ; and there is one among them that has a shorter and stouter rostrum than any which I have seen elsewhere. The broad form appears to be the most common in collections. Bearing in mind the observations quoted from Fischer upon the sexual characters of the skulls of D. delphis and D. tursio, the question naturally arises whether the different forms observed in the skulls of this group may not have the same relation to one another. Unfortunately there are no materials available at present for its solution. The teeth are sculptured in both, but are generally rather more numerous in the narrow than in the broad skulls, being usually 23 or 24 in the former and 20 to 23 in the latter on each side of each jaw. The extreme length of these skulls varies between 520 and 550 mm. A very important contribution to the history of this group of Dolphins has been made by the publication of a good description and figures of both external and anatomical characters of a specimen captured in the South Atlantic in September 1874, in 32° 29' South lat. and 2° 1' West longitude, by the officers of the German ship 1 There are 10 in the British Museum, the same number at Leiden, 6 at Paris, and 5 in the Museum of the College of Surgeons. |