1892] IJO [Cope. 



ofleu splits tlie base and someliiiies tlie length of tlie cliapoplij'sis. Such 

 a structure is seen in Iguanidic (Iguana Sauronialus Sceloporus Dipso- 

 saurus); Anolida'; Anguidte (Celestus); Tiidie (Tupinanibis Cnemidoph- 

 orus) ; Lacertid:i3 (Lacerta) and Scincidsii (Gongylus Eumeces). In 

 Dipsosaurus, Anolis and Lacerta, the neural spines of the caudal vertebrie 

 are double; in the other genera named, single. In Varatiidjx;, Ileloder- 

 midne, Gerrhouotus, Crotaphytus and Phrynosoraa, the caudal centra are 

 undivided, and the neural spines are single. In Ophisaurus the centra 

 are undivided and the neural spines double. The centra are excessively 

 thin in Ophisaurus, so that they break more readily than they disarticu- 

 late. There are two sacral vertebrae except in genera with the posterior 

 limbs rudimental or absent. In some of these however, especially the 

 degenerate genera of the Anguid^e, the rudimental ilium is attached to 

 two diapophyses which join each other distally. 



The first dorsal vertebra is that one which is first connected with the 

 sternum by a bsemapopiiysis. In genera with a well-developed sternum, 

 the number of vertebras anterior to the first dorsal is eight, except in the 

 Varanus niloticiis (Cuvier) and V. griseus, where it is nine. In the 

 extinct Dolichosauria of the Cretaceous period, the cervical vertebrae are 

 stated by Owen to number seventeen. 



The number of ribs attached to the sternum diminishes with the reduc- 

 tion of the limbs, from the normal number of four on each side to one, and 

 total disconnection. A common hsBmapophysis or "xiphoid rod," suc- 

 ceeds these on each side, which gives attachment to two separate hajma- 

 pophyses for ribs. T he common haemapopbysis is a segmentation of the 

 anterior part of the fifth ha3mapophysis, and it is not distinct in some gen- 

 era, as e. g., Sauronialus. In Heloderma, the fifth ha-mapophysis has no 

 sternal segment or connection, and the sixth is wanting. In Varanus the 

 fourth, fifth and sixth are wanting. In genera with the two appendicular 

 htemapophyses, they are closely appressed on the middle line in the 

 majority of the genera, but in genera of depressed form, they are sepa- 

 rated often widely. They are separated in Stenodactylus guttntus, in Phy- 

 maturus, Crotaphytus and Sceloporus. They are more widely separated 

 in Dipsosaurus, and most widely in Sauronialus and Phrynoosma. Cer- 

 vical ribs are present in varying numbers, and the posterior ones are 

 generally quite elongate. In certain genera and families the ribs pos- 

 terior to those attached to the sternum have their hajmapophyses fused 

 on the middle line below, thus constituting a series of abdominal ribs. 

 In the Iguanid genus Scartiscus there are two such ribs. In the Anolidaa 

 there are four and five pairs ; in the Polychroine Iguanidse there are 

 seven to ten. In the Chama^leonidse and Gecconidse there are several 

 pairs. The ribs of Lepidosternum are remarkable for the presence of a 

 capitular process, which has no distinct capitular articulation. 



3. Scapular Arch. — The clavicle is present in all the families except 

 the Chamseleonidae, and in certain genera with depenerate fore limbs. In 

 such genera it is the last portion of the scapular arch to remain, and it is 



