194 REPORT OF NATIONAL MUSEUM, 1898. 



second row, is a single small ceutrale. There are five carpalia, each 

 corresponding to a metacarpal. I have failed to find in any of the 

 genera at my disposal any of the carpalia fused together or wanting. 

 In Chamcvleon, on the contrary, Cuvier has shown that there is no 

 ulnare, and that the centrale and carpalia are fused into a single round 

 median piece, to which the metacarpals are articulated. In all the 

 normal Sauria the tendons of the flexors of the digits are combined 

 on the palm, and the point of junction is occupied by a large flat sesa- 

 moid bone. The number of j)halanges is also remarkably uniform. 

 They number in each digit, commencing with the pollex, 2-3-4-5-3. 

 The sole exception in the genera with well-develoj)ed extremities is 

 Chamwleon, where the numbers are 2-3-4-4-3. This genus differs also 

 from other forms in the shai)es of the metacarpals. Normally they are 

 cylindric and subparallel in i)osition and united in a common integu- 

 ment; but in Chama'leon they are flattened, with expanded extremities, 

 and divided into two bundles by a fissure, three within and two with- 

 out, enabling the three inner digits to oppose the two outer round a 

 branch of a tree. The number of digits in Sauria is normally 5-5, 

 but reductions take place presenting variations from 4-5 to 1-1, the 

 posterior limb usually displaying a lesser degree of degeneracy than 

 the anterior, although not always. 



Posterior limb. — The femur differs from the humerus in having a dis- 

 tinct head, which is marked off from a trochanter. The former is not 

 hemispherical as in Mammalia, but is somewhat compressed, and is 

 oval in section. The trochanter is on the inferior anterior side of the 

 head, or iu the position of the little trochanter of the mammalian femur. 

 There is no great trochanter nor third trochanter. The condyles of the 

 femur are not as well defined as in the Mammalia, and the patellar 

 groove is represented by a shallow concavity without lateral ridges. 

 Patella none, with some exceptional rudiments, as, for example, in 

 Varanus. In Chamcvleon all the prominent features of the femur are 

 toned down, the trochanter being represented by a ridge. The fibula 

 is more slender than the tibia, and is larger distally than proximally, 

 the reverse of what obtains in the tibia. The latter has no crest. 



Like the carpus, the tarsus is very uniform in the Sauria, the sole 

 important modification being exhibited by the Chamicleonidie. There 

 are two fused proximal elements, which are i^robably tibiale-intermedium 

 and fibulare. They are only distinct in Heloderma among North Amer- 

 ican genera, but a trace of the suture is seen in Varanus. In most 

 Sauria there is then but one bone of the i^roximal row, which is flat 

 and wider than long. No centrale, and but two tarsalia, the third and 

 fourth, the latter much the larger. The second metatarsal i^rojects 

 alongside of t. iii, so as to approximate the tibiale; its head is figured 

 by Cuvier as a distinct bone, but he does not describe it as such. In 

 Chamwhon there is a single proximal tarsal element, which is not flat- 

 tened as in other lizards, and this articulates with a single subglobular 



