. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. HISTORY OF MARINE MAMMALS ABEL. 491 While all the series thus far spoken of are still represented to-day, a fourth series, Avhich also took its origin in the squalodons, is entirely extinct. This series comprises the long-beaked dolphins of the Upper Miocene of Antwerp {Eurhinodelphid(B). In one species the snout reaches nine-elevenths of the total length of the skull, an enormous proportion, which stands alone among all the long-beaked aqu
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. HISTORY OF MARINE MAMMALS ABEL. 491 While all the series thus far spoken of are still represented to-day, a fourth series, Avhich also took its origin in the squalodons, is entirely extinct. This series comprises the long-beaked dolphins of the Upper Miocene of Antwerp {Eurhinodelphid(B). In one species the snout reaches nine-elevenths of the total length of the skull, an enormous proportion, which stands alone among all the long-beaked aquatic animals which have lived hitherto. (Fig. 21.) The dolphins of the present are not the descendants of the squalo- dons. "WTiat their ancestors were we can not say to-day. It is sure, however, that they sprang from armored jDrogenitors. In the Upper Miocene of Radoboj in Croatia a small-toothed whale closely allied to the harbor porpoise {PJioccena) has been found whose whole flipper was covered Avith armor, while the existing harbor porpoise retains only scanty remains of this old armor. (Fig. 5.). Fig. 21.—Skull of ii long-beaked dolphin. Eubinodelphis longirostris Du Bus, from the Upper Miocene of Antwerp. Length of skull 106 cm. ( in.). The initial link for connecting the whalebone whales with the land carnivores is also wanting at present. Most probably they originated from the primitive cetaceans. But certainly they passed through the stages of toothed whales, as numerous denticles are present in the jaws of Avhalebone whale embrj'os. The oldest whales of this kind appear in the Miocene. They are very small, but approach very near the finbacks. While, therefore, the origin of some groups of whales is enveloped in obscurity, important and very rich discoveries in the Eocene of Egypt have shown us from what ancestors the sea-cows originated and how their stages of development proceed. Contemporaneously with the oldest primitive cetacean appears the oldest sea-
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