504 CETACEA. 



30 feet ; distinguished from all other cetaceans by preying upon fish, 

 seals, and other cetaceans, with liigh dorsal fin, dentition about f|, 2 

 species, all seas from Greenland to Tasmania ; a Pliocene species known. 

 Pseudorca Reinhardt, all seas, 1 species. Globicephalus Less., nearly all 

 seas ; 6 species ; G. melas Traill, the pilot whale, ca'ing whale, 20 feet, 

 very gregarious and easily destroyed, dentition ~~^- Grampus Gray, 

 Atlantic, Pacific, Mediterranean ; teeth absent in lower jaw, in the mandible 

 3-7 on each side near the symphysis ; 1 species. Feresa Gray. Lage- 

 norhynchus Gray, teeth small, |^, 9 species. 



B. Head with beak ; rostrum of skull longer than the cranium ; atlas and 

 axis united, other cervicals separate. Porpoises and dolphins. 



Delphinus L., teeth ^^^g, small, close set ; pterygoids meeting in the 

 palate ; digits 2 and 3 weill developed, rest rudimentary ; 4 species. D. 

 delphis L., in all seas, common dolphin of the Mediterranean ; 7 feet. 

 Tursiops Gervais, 5 species. Tursio Wagl., 2 species. Prodelphinus 

 Gervais ; 9 species. Ste^io Gray ; 2 species. Sotalia Gray, 8 species, 

 mostly fluviatile or estuarine ; S. teuszii, Cameroon river, fresh-water 

 and apparently herbivorous. S. sinensis Flower, Chinese white dolphin ; 

 S. tucuxi Gray, from the Amazon. 



Sub-Order 3. ZEUGLODONTA* (ARCHAEOCETI). 



Eocene forms of doubtful affinity. The remains upon which the group 

 is based being imperfect it is impossible to arrive at certainty as to whether 

 they should be regarded as primitive Cetacea or as being allied to the 

 pinnipede Carnivora. They were animals of considerable size, attaining 

 a length of over 60 feet. They are said to have had an aimour of dermal 

 plates, t The head is elongated and depressed, the nasal bones being long 

 and the external nares in front on the upper side of the snout. The 

 parietals meet in the sagittal suture, and the sagittal crest is well de- 

 veloped. The frontal roofs over the orbit, and is not overlaid by the 

 maxilla. The cranial cavity is small. These are all non-cetacean char- 

 acters, and it is difficult to see on what grounds such a head as this can 

 be regarded as belonging to that order. To these points of tmUkeness 

 we may add the following. The premaxilla« bear teeth and take part in 

 forming the edge of the upper jaw. The dentition is heterodont, 

 p T^ G \ p and m %, the posterior molars being laterally compressed 

 with two roots and serrated edges like the molars of seals. The cervical 

 vertebrae are separate and not compressed. The ribs are two-headed 

 and the sternum is composed of several pieces. The liunbar vertebrae 

 have elongated bodies. The limbs with the exception of a mutilated 

 liumerus are unknown. Although the four last-named characters are not 

 inconsistent \^dth cetacean affinity, they cannot be regarded as proofs 

 of it, when due weight is allowed to the non-cetacean features of the 

 skull. We have however followed the usual practice of assigning the 

 single genus Zeuglodon Owen to the Cetacea ; Eocene of N. America, 

 Europe, Egypt, and N. Zealand. 



* D'A. W. Thompson, On the systematic position of Zeuglodon, Studies 

 from the M^iseum of Zoology of Dundee, 1890. W. Dames, Ueb. Zeuglo- 

 donten aus Aesvpten etc., Pal. Abh. 5, heft 5, 1894, p. 1. R. T-vdekker, 

 Proc. Zool. Soc'., 1892, p. 560. 



f Abel, Mem-. Mus. Belgique, 1, 1901. 



