Cope.] 



192 



I March 18, 



liypobrancbials are also greatly produced forwards, but carry tbe cerato- 

 hyals with them. Ceratobrancbials of tbe second pair are also wanting 

 iu Varanidse, Helodermidse, ChamiEleonidse, A.nguidse, Anniellida3 and 

 Rbineura ; Phyllodactylus, Thecadactylus and Gecko, among Gecconidse ; 

 and Egernia and Gongylus in Scincid*. Ceratobyals are wanting in Cha- 

 mteleon, Anguis, Anniella and Annulata generally. In both Agamidse 

 and Iguanidae tbe second ceratobrancbials are separated from eacb other 

 in the depressed genera of terrestrial habits, and in close contact with 

 each other in those of arboreal habits ; but they are in close contact in 

 Callisaurus and Crotophytus, both terrestrial genera. In Calotes, Iguana 

 and Anolis they act as the rim on which the gular pouch or fan is 

 stretched. The characters of Lacertilian hyoids may be tabulated as fol- 

 lows : Most of the genera referred to are figured in Plates iii to vi. 



I. Ceratohyal present. 11. Ceratohyal absent. 



A. A second ceratobranchial. 

 a. Free epibranchials present. 



Scincidse. 



Lacertids. 



Xantusiid*. 



aa. No free epibranchials. 



(Scincidae) Mabuia agilis ; Qongylus ocellatics. 



Anolidse. 



Iguanidre. 



Agamidaj. 



Zonuridfe. 



Enblepharidne. 



(Gecconidie) Aristelliger. 



AA. No second ceratobranchial. 

 a. No free epibranchials. 



Rhineiira. 

 ChaniEeleouida; 



Chirotidfe. 

 AmphisbaBnidiC. 



Gecconidae. 

 Varan id tie. 

 Helodermidai 



Tiidae. 



Gerrhosauridie. 



Anguidie. 



Anguis. 

 Auuiellidje. 



3. Vertebral. Column. — Except in the families of the Gecconidai and 

 Uroplatidte, the vertebral centra are proccelous. In the families named, 

 they are amphicoelous. The zygosphen articulation is present in the Tiidae 

 and the larger Iguanida8, including a rudiment iu Crotaphytus. In smaller 

 Iguanidae (Sceloporus Phrynosoma) and in Lacertilia generally this kind 

 of articulation is wanting. In a good many families the caudal vertebrae 

 are divided by a transverse fissure or suture in front of the middle, which 



