34 The Ottawa Naturalist. [May 



The Upper Jurassic compsognathoid form, Ornitholestes 

 hermanni, lately described by Professor Osborn, shews many 

 points of resemblance to its supposed successor Ornitlwniinius 

 alius. Like O. alius it was terrestrial in its habits and a swift 

 runner. The similarity in form of the ungual phalanges of the 

 manus in the two species is strikingly apparent (see figs. 8 

 and 4). Among the remarkable characters of Ornitholestes is 

 mentioned as most distinctive " the narrowing of the manus and 

 the great elongation of the metapodials and phalanges of the 

 second digit, suggesting the rapid grasping power of agile and 

 delicate prey." 



Compared with that of Ornitholesies the manus of Orniihomimus 

 alius is much stouter and less elongated, but it probably had an 

 equally great grasping power. The terminal phalanges curve more 

 rapidly, are proportionately deeper proximally but are less com- 

 pressed laterally ; from those of Orniihotnimtis sedens they differ 

 in being deeper, much more curved and in having a greater lateral 

 compression. 



The phalanges of the manus of Ormthomimus altus repre- 

 sented in the accompanying figures, i — 6, are presumably those 

 of the second digit ; they all resemble those of the pes in being 

 to a certain extent hollow. 



The proximal phalanx is about one-third longer than the 

 second one and about the same length as the distal one. Its 

 proximal end is conspicuously enlarged above and at the sides 

 and the articular surface (fig. \d) is evenly concave. The condyles 

 of the distal end are greatly enlarged in a vertical plane and a 

 deep channelling of the articular surface extends in a curve round 

 the end through an angle of about 223°. Posteriorly below 

 a decided roughening of the surface of the bone occurs for muscu- 

 lar attachment. 



The second phalanx (fig. 2) is short above but a backward 

 extension of the inferior surface adds greatly to ils length below. 

 The proximal articular surface exhibits a sharp vertical keel, on 

 either side of which the bone is well excavated ; the distal surface 

 has a decided medium groove extending through an angle of 180°. 

 The enlargement below the proximal articular face combined with 

 a well-defined roughening of the bone suggests great muscular 



