184 REPORT OF NATIONAL MUSEUM, 1898. 



is wanting and in most cases is fused with the postorbital in the 

 VaranidjE and Agamidjc; but in other families it is distinct, with 

 sporadic cases of fusion, as in Cnemidophorus. Superciliary bones 

 are present in Yaranus, Phrynosoma, and several genera of Agamidte. 

 They belong to the tegumentary system, and articulate the anterior 

 with the prefrontal, the posterior (absent in Varanus) with the post- 

 frontorbital bone. The sujoraoccipital is undivided and forms the 

 superior part of the edge of tlie foramen magnum. Its anterior bor- 

 der is generally loosely articulated with the parietal, joining it by 

 a rudimental or developed median gomphosis with the supraoccipital 

 process. It is generally overhung by the parietal, always so when 

 the parietoquadrate arches are present. It is entirely overroofed by 

 tlie i^arietal in the Xantusiid;e, the two elements being connected by a 

 vertical laminiform septum. It is not overhung in the Annielloidea 

 and Amphisba^nia, and in these the articulation is a firm complete 

 transverse union. The parietoquadrate arch consists proximally of a 

 process of the parietal, which is directed outward and posteriorly, 

 which may represent the supramastoid element of the primitive Coty- 

 losauria. Distally this process receives an ascending process of the 

 paroccipital on its inferior aspect, sometimes anteriorly, sometimes pos- 

 teriorly. This arch is shortened and depressed in the Anelytropsidse 

 and is absent from the Anniellid;E and Amphisbflenia. In the Chamie- 

 leonidfB it is differently composed, consisting of a superior i)Osterior 

 process of the supratemporal, which rises upward and reaches the 

 produced apex of the undivided parietal. The supratemporal is accom- 

 panied for a short distance above the quadrate by the ascending 

 l^rocess of the paroccipital. The pineal foramen is present in the 

 Chama?leonid;B, Agamidfe, Iguanid;e, Anolidu^ Xenosauridte, Anguidie, 

 Lacertida% Yaranidte, and Scincida\ It is wanting in the Helodermidiie, 

 Eublepharida), Teiida^, Anniellidic, and in the Amphisbtenia. It perfo- 

 rates the i)arietal bone clear of all sutures in most of the families, but 

 it is near to or on the frontoparietal suture in Iguanid^e and Anolidne, 

 and is in the frontal in Dipsosanrm and the Ohaimeleonidoe. The occi- 

 pital condyle is compound, consisting of portions of the exoccipitals 

 and basioccipital. In many genera these segments become so thor- 

 oughly coossifled at maturity as to be undistinguishable. In some of 

 the Geckonida) (as Geclw, Uroplates) the occipital segment is so reduced 

 as to give the appearance of two condyles. In the Amphisba^nia the 

 condyle is transverse and concave at the center, leaving the lateral 

 portions iirominent. 



The postorbital bone when present sends a process posteriorly to the 

 supratemporal, forming the supratemporal arch. In the genera without 

 this arch the postorbital may be wanting, as in Heloderma, or be rudi- 

 mental, as in Anniella. In the genera whose degeneration is advanced 

 the supratemporal bone is appressed to the parietal, inclosing no 

 foramen supratemporale, as in Feylinia. In limbless genera of Anguidfe 



