CROCODILIANS, LIZARDS, AND SNAKES. 205 



Evesia, while the hind limbs have disappeared, the scapular arch has 

 many points in common with Uve.sia. Thus, the clavicle and interclavi- 

 cle are simple, and the sternum has only two costals. The scapular 

 and clavicle are much better ossified. On the other hand, the pelvic 

 arch displays a great reduction. In Anelyfropsis, appropriately to the 

 absence of fore limbs, there is no scapular arch. The pelvic arch is 

 greatly reduced; but, curiously, there appears an element which resem- 

 bles a corresponding element in the snakes. This arrangement is quite 

 dift'erent from anything observed in the other Leptoglossa or in the 

 Diploglossa, but is not without parallel in other Sauria, to be described 

 later on. 



The reduction of the scapular elements proceeds in the Leptoglossa 

 on much the same lines as observed in the Diploglossa. The early sim- 

 plification of the distal end of the clavicle is peculiar to the Leptoglossa 

 as it is always simple in the Diploglossa. The late stages of reduction 

 of the sternum seen in the limbless Diploglossa are not exhibited by 

 any of the forms here described, although they probably exist, since 

 we have the Anelytrojms, where the scapular arch is wanting. On the 

 other hand, the extreme reduction of the pelvis seen in Propus^ where 

 the ilium only remains, has not yet been observed in the Diploglossa 

 without posterior limbs. 



Observations on Annulati. — The wide diversity between the pelvic 

 structure in Chirotes, as compared with that of Amphishcena, emphasizes 

 the evidence furnished by the scapular arch in favor of regarding it as 

 representing a family distinct from the Amphisbteuidfe. Even with 

 the pelvic elements of Ghirotes before us, it is difficult to be sure of 

 the homology of the corresponding part in Amphishcena and Rhineura. 

 It can only be one of the two inferior elements, or femur. Against the 

 latter supposition, wliich is suggested by the structure of the Anely- 

 tropidic, its anterior position is strong evidence. For the reason that 

 it approximates closely the vent, its claim to be ischium is rather 

 stronger than the supposition that it can be pubis. It is homologized 

 by Fiirbringer with the iliopectineal bone of the snakes. 



General conclusions. — One conclusion is obvious, and this is that 

 degeneracy of the scapular and pelvic arches follows degeneracy and 

 loss of limbs, sooner or later. More special conclusions may be 

 expressed as follows: 



I. Anterior limbs have disappeared more generally than the posterior 

 in tlie Diploglossa. 



II. The limbs incline to degenerate and disappear more nea,r\y pari 

 passu ill the Sciucida'. 



III. The anterior limbs have a tendency to persist longer in the Teiidai 

 and Amphisb;enidie. Future research may not sustain this proposition. 



IV. The degeneracy in the scapular arch is delayed long after the 

 degeneracy and loss of the anterior limbs. 



V. Degeneracy of the pelvic arch precedes the loss of the pelvic limb. 



