الفهرس 
ِAcknowledgementOnly 14 pages are availabe for public view
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Abstract
In the present study, 4 species of lizards were chosen from three different families, Gekkonidae (Stenodactylus petrii), Lacertidae (Acanthodactylus boskianus), and Scincidae (Scincus scincus, and Sphenopus sepsoides) were collected from different localities in Egypt. The present study shows the variations in morphology, histology of the skin of the digits, osteological [characters of the fore and hind limbs and locomotion pattern of these lizards.
The gross morphological and histological study of the skin of the digits showed a wide range of variations. The skin of the digits showed distinctive modifications for digging or swimming in the sand and modifications of the skin are considered as a correlation with the environmental and functional demands. The digging non- climber gecko and other lizard families lack ”the scansorial pads”. The soft dune- dwelling lizards carry on their digits lateral fringes facilitating movements on soft sand. Sensilla are present only in S. petrii. These sensilla are common on paralamellar scales and it bear a single central bristle.
The present study showed that the skin of the digits consists of elevated scales that differ in shape between the different families. There are two types of g;ales; overlapping and tubercular scales. The ventral scales are more overlapping than the dorsal scales. The skin of the digits showed that the scincids and lacertids have overlapping scales, and the hinge regions separate Hie scales and facilitate movement of the body. Collagen fibers are distributed through the dermis, particularly in the stratum compactum (lower dermis).
The skin is an ecological indicator, where the thickness of the epidermis Kay be ecologically correlated. The presence of different functions of the digits leads to wide variations in the gross morphology and skin histology of these digits.
Osteological study showed that the pectoral girdle elements are stable in [the number, and the carpus consists of eight elements while in the lacertid there is an additional element (intermedium). The present study confirmed that the pelvic girdle has essential elements which are quite distinct or completely fused among the present lizards, and the tarsus consists of the proximal tarsal element land tarsalia 1,3 and 4 and sometimes tarsalia 1 is missing in some lizards.
The phalangeal formula of the manus and pes of the species studied were identified and tabled. It was found that there are 4 different phalangeal formula in the skink S. sepsoides.
The arrangement of calcified centres of the epiphyses of long bones and phalanges were identified and the calcified epiphyses are always separated from the diaphyses by a growth zone.
The present investigation illustrates and tabled the distribution of different types of sesamoids which associated with the elbow and knee. Also, the present study confirmed that the cartilage canals are absent in all species studied.
The comparison between the present lizards with other lizards indicates mat there are invariant patterns in all reptiles. The skeletal elements of the hand and foot exhibit several feature reflecting the specialized method of locomotion, and are related to remarkable adaptations of claws, fringes, scales and sesamoids. The relationship between these elements and adaptation to digging and swimming in the sand is illustrated.
So, locomotion analysis of the present lizards showed that the sprawling locomotion is the common feature of the locomotion, and that the digging lizards have no ability for climbing the vertical surfaces. The digging lizards Bowed no digital inflection during the locomotion. However, the locomotor pattern of the present lizards is nearly identical and consists of protective and propulsive phases.
Finally, locomotion is essential in many ecologically relevant functions feeding and predator avoidance). It consists of several components (speed,
acceleration, endurance and maneuverability) and modes (level running, digging and swimming).