Cope.] J-^^ [March 18. 



face of the muzzle. The nasal bones are generally distinct, but in the 

 Varanidie they are fused into a single narrow median element. In the 

 Chama3leonidii3 they do not attain the nasal border, being cut off by the 

 junction of the prefrontal with the premaxillary and maxillary bones. 

 In the genus Feylinia the nasal bones are fused into a broad plate. In 

 Lepidosternum they are completely cut off from the nasal border by the 

 maxillary, which is broailly in contact with the premax'llary spine. In 

 Rhineiira the nasal bone reaches the nares as in Amphisbfena. The 

 frontal bones are separate in the Varanidaj, Helodermidne, Anguid*, 

 ScincidtiB, Anelytropidoe, Anniellidas and Amphisbrenidse, and in some 

 Geccouidse. They are coossified in some Gecconidae ; in the Iguanidge, 

 Agamidse, Xenosauridse, Eublepharidte, Chamseleonidae and Tiidge. 

 The parietalsare generally fused, the only exception being the Gecconidse, 

 Uroplatidse, and Xantusiidte. Prefontals are always present, and in 

 Anniellidse, Helodermidai and Chamseleonidce they extend posteriorly 

 to the postfrontals, excluding the frontal from the orbital border. Lach- 

 rymals are present, but they are fused with the prefrontal in the Scin- 

 cidae. The jugal is generally present, even when there is no postorbital 

 arch, as in Gecconidse, where it is a splint ; but in the Amphisbaenia, 

 Annielloidea, and in Feylinia, the splint-like element attached to the 

 maxillary extends to the pterygoid posteriorly and the prefrontal ante- 

 riorly, and may include the lachrymal. The jugal extends anteriorly 

 as far as the lachrymal except in the Scincidie. The postfrontal is want- 

 ing and in most cases is fused with the postorbital in the Varan idse and 

 Agamidae ; but in other families it is distinct, with sporadic cases of 

 fusion, as in Cnemidophorus. Superciliary bones are present in Va- 

 ranus, Phrynosoma and several genera of Agamidse. They belong to 

 the tegumentary system, and articulate, the anterior with the pre- 

 frontal, the posterior (absent in Varanus) with the postfrontorbital bone. 

 The supraoccipital is undivided and forms the superior part of the edge 

 of the foramen magnum. Its anterior border is generally loosely articu- 

 lated with the parietal, joining it by a rudimental or developed median 

 gomphosis with the process supraoccipital. It is generally overhung by 

 the parietal, always so when the parietoquadrate arches are present. It 

 is entirely overroofed by the parietal in the Xantusiidse, the two elements 

 being connected by a vertical laminiform septum. It is not overhung la 

 the Annielloidea and Amphisbsenia, and in these the articulation is a 

 firm complete transverse union. The parietoquadiate arch consists proxi- 

 maliy of a process of the parietal, which is directed outwards and poste- 

 riorly, which may represent the supramastoid element of the primitive 

 Cotylosauria. Distally this process receives an ascending process of the 

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

 riorly. This arch is shortened and depressed in the Anelytropidse and is 

 absent from the Anniellidaj and Amphisbaenia. In the Chamseleonidte 

 it is differently composed, consisting of a superior posterior process of the 

 supratemporal, which rises upwards and reaches the produced apex of the 



