562 MR. R. LYDEKKER ON ZEUGLODONT [NoV. 1, 



II. Undetermined Cetacean. 

 (? Platanistidce.) 



The second species in the collection is represented by an associated 

 series of four cervical, and the first dorsal, a lumbar, and a caudal 

 vertebra ; one of the cervicals being represented in PL XXXVII. figs. 

 1,1a, and a caudal in figs. 2, 2 a of the same. The vertebrae indicate 

 a Whale of the approximate size of the existing Beluga, with the last 

 four cervical vertebrae free and of moderate length, and the lumbars 

 and caudals likewise of medium elongation. The form of both the 

 cervical and caudal vertebrae shows that these specimens are not 

 referable to Zeuglodon caucasicus. The cervical vertebrae are 

 represented by their centra, with the roots of the transverse pro- 

 cesses attached ; the figured example having a width of 3"1 inches, 

 a height of 2*2 inches, and an inferior length of 1 inch. The lumbar 

 has a length of 2* 3 inches, and a width of 2' 6 inches across the 

 anterior face of the centrum. 



With regard to their affinity, it is clear, in the first place, that, as 

 they belong neither to Monodon or DelpMnaptervs, they cannot be 

 referred to any other existing genera of Belphinidce, in all of which 

 the first two cervicals are united, and the remainder extremely short, 

 and generally more or fewer of them anchylosed. Free cervicals 

 occur in the existing SdlcBnoptera, Megaptera, and Rhachianectes, 

 and the extinct Cetotherium. The small size of the specimens 

 renders it, however, somewhat improbable that they belong to the 

 Balcenidee ; and to this it may be added that they differ in certain 

 respects from those of Balcenoptera. Moreover, we have no definite 

 evidence of the occurrence of Baleen Whales in the Lower Mioceue, 

 to which it is quite probable that the Caucasian strata may belong. 



The existing Platanistidce and the numerous fossil forms referred 

 by Prof. Cope to that family all have free cervicals, and, from the 

 resemblance of the present specimens to some of the Miocene American 

 representatives of that group described by that writer, I am inclined 

 to think that they should be referred to the same family. The 

 resemblance appears to be closest with the series of vertebrae figured ^ 

 as Ixacanthus, and I am by no means certain that the Caucasian 

 specimens do not indicate a member of the same genus, of rather 

 larger size than its typical representative. Still, howevei', I do not 

 propose to make any definite determination, leaving the matter with 

 the expression of my opinion that the specimens probably belong to 

 the Platanistidce. 



III. Iniopsis caucasica («. g. et sp.). 



The third Caucasian Cetacean is indicated typically by the hinder 

 portion of a cranium, and also by some fragments of jaws and several 

 vertebrae probably referable to the same form. It is much in- 

 ferior in size to the preceding, and was of rather smaller dimensions 

 than the existing Inia : that is to say, its total length was some six 

 feet. 



• Cope, Amer. Nat. 1890, p. 603, fig. 1. 



