1 Ql 



]8o9.] ^•^'- [Cope. 



this point is deep witliiii the alveolus. It is therefore much sliorter, even 

 supposing its extremity to have been broken off, and worn on the frac- 

 tured surface. Both the above genera possess a layer of enamel on the 

 external, and a sheath of cementum on the internal side; in this genus 

 there is a thick sheath of cementum all round. The plane of the worn 

 surface is in Halicore oblique to the short diameter of the shaft of the 

 tooth (see Lartet on Rhytiodus, Bull, de la Soc. Geol. de France, 1866, 

 PI. XIII), while in the present species it is oblique to the long diameter. 



Hemicatjlodon epfodiens, Cope sp. nov. 



Tlie transverse diameter of this tooth is greater anteriorly tlian poste- 

 riorly. The ribs of the dentine are strongly marked and distant. The 

 dentinal layer is about one half the thickness of the osteodental axis, and 

 tliree times that of the cementum. 



Metres. 



Greatest length of specimen 015 .00 



" diameter 007 .40 



Least " 004.50 



The external surface of the cement is slightly rugose from interrup- 

 tions of striae. The widths of the tooth increase very little from the basis 

 to tlie worn surface. 



The only specimen of this remarkable species which I have yet seen is 

 considerably larger than the corresponding portion of the Indian Dugong. 

 It was first brought to notice by Dr. Samuel Lockwood, of Keyport, Mon- 

 mouth CO., ]Sr. J., who obtained it from the Eocene mai'l pits at Shark 

 River, Monmouth co. 



EXPLANATION OF THE PLATES. 



PLATE III. 



Fig. 1. — 1 a. Galera perdicida, Cope. 

 " 2. — 2 a. Mixophagus spelaeus. Cope, double nat. size. 

 " 3. — 3 a. Sterodectes tortus, Cope, external and posterior views of 

 superior incisor. 

 Fig. 4. — Tamias laevidens, Cope, double nat. size. 

 " 5. — Sciurus panclius. Cope, 5 a, right ramus of mandible from 

 above; both double nat. size. 



Fig. 6. — Tapirus haysii, Leidy, inferior molar; 6 a, another inferior 

 molar, from above. 



The above are of the natural size, except where stated otherwise. 



PLATE IV. 



Fig. 1. — 1 a. Amblyrhiza inundata, Cope, inferior incisor; 1 a, from the 

 outside; nat. size. 



Fig. 2. — Do. molar, from behind; 2 a, crown, grinding surface, nat size. 

 " 3. — Do. two posterior sujjerior molars from the side; 3 a, grinding 

 surface; nat size; 3 b, root of do. from behind. 



Fig. 4. — Do. right femur, from above; 4 a, distal end of same, slightly 

 restored from specimen of fig. 5. One half nat. size. 

 A. P. S. — VOL. XI — Y 



