No. 2.] THE RELATIONS OF PROTOCERAS. 355 



the same size. The dorsal border of the facet is prolonged in 

 the median line into a large overhanging hook, which is but 

 slightly indicated in the anterior ungual. This hook corre- 

 sponds to the greater dorso-plantar diameter of the distal 

 trochlea of the second phalanx and its greater prolongation up 

 the dorsal face of the shaft in the pes than in the manus. 



As will be seen on comparison of the tables of measure- 

 ments, there is not in MoscJms such a difference between the 

 anterior and posterior phalanges as obtains in Protoceras. 

 Those of the pes are of nearly the same size in both genera, 

 though slightly larger in Protoceras, while those of the manus 

 are considerably larger in MoscJms. In structure also the pos- 

 terior phalanges agree better in the two animals, the differ- 

 ences being merely in matters of minute detail, except, of 

 course, the grooves for the metatarsal keels. 



Measurements. 



Protoceras. Moschus. 



Ilium, length of ventral border (fr. acetabulum) . . o.ii6 0.069 



Ilium, depth of neck 023 .011 



Acetabulum, fore and aft diameter 024 .020 



Acetabulum, vertical diameter 020 .019 



Femur, length 177 .164 



Femur, breadth of proximal end 042 .035 



Femur, breadth of distal end 041 .032 



Patella, height 036 .025 



Patella, breadth 024 .013 



Tibia, breadth of proximal end 039 .035 



Tibia, thickness of proximal end 046 .037 



Calcaneum, length 070 .051 



Astragalus, length 030 .022 



Astragalus, breadth of proximal trochlea 016 .015 



Cuboid, height 016 .008 



Cuboid, breadth of distal end on .008 



Metatarsal III, length 107 .131 



Metatarsal III, breadth of proximal end 012 .007 



Metatarsal III, breadth of distal end 013 .009 



Metatarsal IV, length 107 .134 



Metatarsal IV, breadth of proximal end on .008 



Metatarsal IV, breadth of distal end 012 .009 



First phalanx, III digit, length 035 .031 



First phalanx. III digit, breadth of proximal end . . .013 .010 



First phalanx. III digit, thickness of distal end . . .009 .009 



Second phalanx, III digit, length 022 .023 



