1892.] AND OTHER CETACEAN REMAINS. 559 



three distinct forms, one of which was a Zeuglodont, the second a 

 more typical Cetacean of relatively small size, and the third a still 

 smaller dolphin-like Cetacean. The Zeuglodont remains indicate 

 a very small species. 



In regard to the probable age of the deposit, it may be observed 

 that although Zeuglodonts occur in America in the Middle Eocene, 

 and in England in the lower part of the Upper Eocene (Barton beds), 

 in Malta they are found in the Miocene, where one of the forms is 

 of very small size. Moreover, since, with the exception of Zeuglodon 

 and Squalodon, together with the problematical Balcenoptera (?) 

 juddi, Whales are unknown in the Eocene, while we have two 

 distinct forms in addition to the Zeufjlodon from these deposits, 

 it might seem that the age of the latter is Miocene rather than 

 Eocene. So far as it goes, the evidence of the Zeuglodon might 

 be in favour of the same view, since such a small form as the one 

 before us might well be one of the last waning representatives of 

 its race. 



With these preliminary remarks, I proceed to the consideration of 

 the specimens themselves. 



I. Zeuglodon caucasicus, sp. nov. 



The Zeuglodont remains comprise the hinder part of a left 

 mandibular ramus containing four teeth (PI. XXXVI. fig. 1), 

 another fragment of a jaw with five broken teeth, a left humerus 

 (PI. XXXVI. fig. 2), and an imperfect caudal vertebra (PI. XXXVI. 

 fig. 3). 



The Zeuglodont nature of the figured jaw is shown by the teeth, 

 in which the serrations are as fully developed on the anterior as on 

 the posterior border, thus differentiating the specimen from the 

 Squalodonts. The jaw is relatively deeper than in the so-called 

 Zeuglodon hydrarchus ' of North America, but the chief peculiarity 

 of the specimen is its small size, which at once distinguishes it from 

 the American form. 



The humerus (PI. XXXVl. fig. 2) agrees in relative size with the 

 jaw, its total length being only 4'4 inches, whereas the corresponding 

 bone of ^. hydrarchus preserved in the Museum at Haarlem measures 

 8"6 inches ^. In character both specimens agree very closely, although 

 the European example is distinguished by the greater development 

 of the deltoid crest {d), the more oblique form of the head (A), and 

 the less upward extension of the great tuberosity {t) ; the upward 

 extension of this tuberosity in the Caucasian specimen is, however, 

 at least partly due to the effect of crush. Both bones are distin- 

 guished by the large size of the head, the compressed form of the 



1 Dames and Gaudi-y regard this form as the female of the larger Z. cetoides, 

 but Cope (Amer. Nat. 1890, p. 602), who alludes to it as Z. hrachys'pondylus, 

 considers that it may belong to a' distinct genus — Boryodon. That genus is 

 typically represented by the smaU Doryodon pygmmis, Leidy. 



2 There is a cast of this bone in the British Museum. 



38* 



