24 ANNALS NEW YORK ACADEMY OF SCIENCES 



other features with the older stages of the Halicorid*. The axis agrees 

 with the same types, comparing with Ealitherium, hut is less certainly 

 identifiable. 



The lower jaw found by Dr. Reeds is clearly distinct from Prorastomus 

 and from the modern manatee (Manatus == Trichechus) , and appears to 

 be related to Halitherium of the European Oligocene. Unfortunately the 

 front of the jaw is missing, so that the identification is in some degree 

 provisional ; but the form, proportions and spacing of the teeth preserved 

 or indicated by their alveoli agrees with this genus, as does also the form 

 of the lower jaw. It is with some hesitation that I refer it to an Old 

 World genus, but the known range of the manatee in Africa and tropical 

 America, with fossil representatives in Belgium as well as along the At- 

 lantic coast of the United States, makes it quite reasonable to believe that 

 Halitherium also ranged on both sides of the Atlantic in Tertiary times. 

 Its modern descendants, the Dugongs, are found in the Indian Ocean and 

 Eed Sea. 



The lower jaw here described is about the size of a manatee jaw, and 

 with the same great depth of angle, high condyle, heavy coronoid process, 

 deep pter3^goid fossae. It is much deeper and heavier posteriorly than in 

 Prorastomus and somewhat deeper under the molars. Three molars are 

 preserved. Although badly worn and the inner sides much damaged by 

 weathering, it is evident that they were rather short-croAvned teeth of the 

 usual primitive sirenian pattern of five robust cusps arranged in two 

 cross-crests and a small heel. The last molar was apparently considerably 

 longer than the second, with a much more distinct heel supported on a 

 small median posterior root which the anterior molars lack. The first 

 molar appears considerably smaller than the second, but this is chiefly 

 due to its being more worn. Of the differentiation of Wg from m^ and mg 

 there is no question. The premolars are indicated by alveoli. P4 (more 

 probably dp^) was two-rooted, much smaller than m^. Pg has a single 

 oval root, with a diastema behind it equal to its o^^ai greater diameter. 

 Po is doubtfully indicated by an obscure round alveolus with a diastema 

 separating it from p^. 



In front of this the jaw is broken off obliquely and it is impossible to 

 say what it was like. So far as they go, the characters agree with Hali- 

 therium schinzi, save for the somewhat shorter and deeper posterior por- 

 tion of the jaw, smaller molars, and greater rediiction of the premolars. 

 From Manatus the jaw differs in the reduction of the premolars and dif- 

 ferentiation of the last molar; from Prorastomus in the much greater 

 depth of the jaw posteriorly, reduction of the premolars and larger size 

 of the molars. 



