ON THE OSTEOLOGY OF NyYCTOSAURUS. I51 
extending further, is much less in extent. The inner distal articular sur- 
face is the larger, and is separated from the inner surface by a distinct 
ridge, especially posteriorly. 
Tibia. Pl. XLIV, Fig. 3. The tibia is a slender, straight bone, mod- 
erately expanded at the upper extremity. The margin of the articular 
surface above is nearly transverse to the longitudinal axis. The width 
contracts chiefly at the expense of the posterior margin to the lower part 
of the upper fourth of the bone, the shaft below being of nearly uniform 
width. The trochlear surface at the distal extremity is pulley-shaped, 
covering about half of a circle, perhaps more, and has a moderately 
deep groove. ‘The sutural union between the tibia proper and the prox- 
imal tarsal bone, or bones, is entirely obliterated. ‘The bones of the two 
sides are compressed in different positions, the left one from the side, the 
right one from nearly in front; the width above is considerably greater 
in the former than in the latter, indicating but comparatively little ex- 
pansion of the upper part from side to side. 
There is no trace of any fibula, either in the preserved remains or in 
any tibial articulation. 
MEASUREMENTS OF TIBIA. 
en ee ee a soe Ane 133 (132) 
SS a eee RS el SE 9 15 ( II) 
Reet eaiiatt-al upper end/of middle third._-- -2--_2.----w.-----.=-- vel te ke) 
REM NTC) ee tee ee tee ee oe 8 eee 5-22 6( 6) 
pee eee eriorCiamierer of trochlea 2202 22 <2 2S. -..--- 2. 2-4 --- 6( 4) 
foot. Buta single metatarsal and one phalange are present in this 
specimen. ‘These, however, agree so well with the corresponding bones 
of Preranodon that I doubt not the foot was quite similar to that of the 
former genus. This metatarsal is expanded at its proximal end and 
gently convex on the trochlear end. It measures 35 mm. in length, 2mm. 
in width at the upper fourth and 4 mm. at either extremity. The bone is 
compressed from side to side. The phalange, flattened on the side, has 
a length of 14mm. The distal end has the extremity convex, its chord 
rectangular to the long axis of the bone; its width is 3mm. The 
proximal end is truncated or gently concave ; its width is about 4 mm. 
The shaft in the middle is scarcely narrowed from the proximal end. | 
repeat here, briefly, the description of the foot of Pteranodon, from my 
paper in the Kansas University Quarterly, vol. vi, page 50, with some 
changes. 
The first four metatarsals are very slender, straight, and contiguous 
with each other, each having a flattened proximal articular surface and 
a rounded trochlear distal extremity. The metatarsal of the fifth toe is 
