Nu. lOSO. 



THE FOSSIL (IE MIS PTILODUS—CilDLEY 



621 



^i* Q) 



Fui. :{. — Teu.minal 



PHALANX OF I'TI- 

 LODUS GRACILIS. 

 T Y P E. a, SIUK 



VIEW ; h, rnox- 

 imm. end view. 

 Twice nat. .size. 



vers( 



Iv 



IF I'ELN IS OF rTILODUS GRACILIS. 



VIEW. Twice nat. size. 



Type. Outer 



The feet are represented by an uiio-unl phalanx (fio^. ;^) and two 

 or three portions of nietapodials. The.se bones, 

 which from their rehitively small size apj^arently 

 belong; to the fore feet, are rather long- and slender 

 in proportions and not specialized. The nngnal 

 phalanx apparently sup})orted a rather sharp claw. 

 The pelvis is proportionately large but ])rimitive 

 in structure^ (See fig". 4.) The illium is a long", 

 slender, rod-like bone, somewhat flattened trans- 



The ischium is moderately long- and expanded. Unfor- 

 tunately t h e 

 greater part of 

 t h e pubis is 

 broken away so 

 that the pres- 

 ence or absence 

 o f marsupial 

 bones can not 

 be determined, 

 although they 

 probably were 

 present. The 



obdurator foramen, as indicated by its upper l)order, which is pre- 

 served, is (■()mi)ai-atively small. 



The femur (see fig. 5) is relatively large and 

 stout as compared with the humerus. Both 

 trochanters are well developed, the great tro- 

 chanter extending considerably above the head 

 of the fennir. The lesser trochanter is a promi- 

 nent tubercle, and is situ- 

 ated on the posterior face 

 of the shaft near the base 

 of the great trochanter as 

 in the eutherian mammals. 

 The shaft is nearly straight 

 and is slightly flattened an- 

 teroj:)osteriorly. 



The tibia and fihuJa (see 

 fig. fi) are poorly preserved, 

 but are represented by por- 

 tions of the proximal ends. 

 The tibia is much the larger 

 bone. Both are large as 

 compared with the radius 

 and ulna. The relatiA^ely large proportions of 

 the pelvis and hind limbs strongly suggest that Ptilodus was salta- 

 torial in habits. 



Fig. 5. — Right fe.mur of 

 Ttilodus gracilis. 

 Type. Tosteriorview. 

 Twice nat. size. 



Fig. G. — I'roxi JiAL por- 

 tions OF tibia and 

 fibula of Ttilodus 

 GRACILIS. Type. 

 Posterior oblique 

 VIEW. Twice nat. 



SIZE. 



