OSTEOLOGY OF POLYGLYPHANODON—GILMORE 263 
The five metatarsals increase in length progressively from the first 
to the fourth, which is the longest of the series. The fifth is the 
shortest and is further distinguished by the great winglike expansion 
of its upper end, as in Jguana and Cyclura. In the articulated foot 
this expansion of the fifth metatarsal extends inward behind meta- 
tarsal IV and articulates along its upper border with the cuboid, little 
if at all with the caleaneum. The fifth metatarsal is strongly bent, 
as inthe Chelonia. In articulation the other metatarsals are somewhat 
imbricated, the dorsal margin overlapping the thinner inner side of 
the next outer bone. 
The phalangial formula is the primitive one of 2, 3, 4, 5,4. All 
the digits are terminated by sharp compressed unguals. The meta- 
tarsals of U.S.N.M. No. 15568 have the following lengths: I, 18.3 mm.; 
II, 27.4 mm.; IIT, 33.5 mm.; IV, 36.0 mm.; V, 13.0 mm. 
Insofar as comparison is possible, the tarsus of Polyglyphanodon 
shows the closest resemblances to that of Jguana. That remark applies 
equally well to the foot. The phalangeal formula, the relative length 
cf the phalangials, and of the digits as a whole, are in almost perfect 
agreement with the pes of Zguana. The only difference worthy of 
mention is that the individual elements are somewhat stouter than in 
an Iguana of equivalent size. 
Patellar sesamoids.—A small diamond-shaped ossification attached 
by matrix to the posterior side of the distal end of the right humerus 
of specimen U.S.N.M. No. 15816 appears to represent the patella 
ulnaris. Its position in situ gives support to such a conclusion, for, 
as Camp® points out, “the patella ulnaris hes in the tendon of 
insertion of the triceps which rides over the end of the humerus 
to reach the olecranon.” 
This sesamoid is partly bony in most of the Ascalabota and carti- 
laginous in most Autoarchoglossa. Fiirbringer,’ however, is inclined 
to place little significance in either its form or distribution in lizards, 
The patella tibialis is present in three specimens, U.S.N.M. Nos. 
15816, 15817, and 15868. This is a small, irregularly shaped, ossicle- 
like bone that in most instances is attached by matrix to the distal 
end of the femur. In one instance it was found lying in the matrix 
between the proximal ends of the tibia and fibula. 
A second but smaller ossification attached to the distal end of 
the right femur of specimen U.S.N.M. No. 15816 may be the fibular 
interarticular sesamoid, which is sometimes developed in the femoro- 
6Camp, C. L., Classification of the lizards. Bull. Amer. Mus. Nat. Hist., vol. 48, p. 
408, 1923. 
7¥Fiirbringer, Max, Zur vergleichenden Anatomie des Brustschulterapparates und der 
Schultermuskeln. Jenaische Zeitsehr. Naturw., vol. 34 (new ser., vol. 27), pp. 443-444, 
1900. 
