Pectoral Girdle
(Fig. 5.)

In the New Zealand genera the sternum is a more or less rhomboidal plate which in Naultinus is either only slightly calcified or not at all. It is not fenestrated. According to Camp (1923), sternal fenestrae, which are present in most families of lizards except the Anguimorpha, are probably sometimes of secondary development, perhaps connected with certain relationships of the pectoralis musculature.

Two ribs are attached to each postero-lateral side of the sternum. One or more of the succeeding pairs of ribs, though not attached directly to the sternal plate, join two parallel rods forming the xiphisternum. The number of pairs of ribs doing so varies and is greatest in Naultinus. The xiphisternal rods run close to the middle line and join the sternum at its posterior end.

The interclavicle has an irregular, sub-rhomboidal shape in Naultinus, but is distinctly sub-cruciform in Hoplodactylus, especially in H. pacificus. According to Camp (1923), with increasing reduction from the sub-rhomboidal and sub-cruciform, only a splint-like, longitudinal element remains in Paragonatodes, while a mere nodule occupies the position of the interclavicle in Uroplates.

The clavicles in Naultinus and Hoplodactylus are slightly dilated mesially. Those of Naultinus are imperforate, while those of Hoplodactylus may have one or two fenestrae. Noble (1921) has shown in a series of geckos how the clavicle might have been gradually expanded and in the extreme stage thinned out until a foramen was formed. On the other hand, Camp (1923) expresses his belief that modern Sauria are derived from ancestors with broadly expanded, non-perforate clavicles, and that simple rounded clavicles have been shaped from these.

The distal end of each clavicle articulates with a notch or depression on the antero-ventral region of the suprascapula, just as in Hemidactylus (Mehendra, 1950). This relationship to the suprascapula, which far from being confined to certain geckos occurs also in such forms as Iguana tuberculata (Goodrich, 1930), contrasts with the condition in Sphenodon and in many Lacertians where the clavicle abuts against the scapula which usually has a well-developed acromial process to receive it.

Fenestration in the scapulo-coracoid region is not as extensive as in most geckos. Hemidactylus is figured (Mahendra, 1950) to have four fenestrae on each side apart from the supracoracoid foramen. These are presumably scapular, scapulo-coracoid, lateral coracoidal and median coracoidal fenestrae. In both Naultinus and Hoplodactylus, the coracoid and scapula are often indistinguishably fused together, but the line of fusion is sometimes clear in Naultinus This indicates that of the two fenestrae present, one is the scapulo-coracoid fenestra and the other a coracoidal fenestra. A fairly large supracoracoid foramen is present.

The two epicoracoids are flat plates, convexly curved along their inner borders. They are well calcified in Hoplodactylus but uncalcified in Naultinus The epicoracoids in both genera overlap in the middle line, the left ventrally to the right, and they are able to do this because the sternum is more posteriorly placed in relation to them. This contrasts with Hemidactylus (Mahendra, 1950), where although the sternum is in similar position the epicoracoids do not meet in the mid-ventral line, and with such lizards as Calotes versicolor (Iyer, 1942) where the epicoracoids are kept far apart by the presence of a broad sternum between them.