. A manual of zoology. Zoology. fiOO GIIORDATA. Sub Order II. PYTHONOMORPHA. Large, extinct, extremely elon- gate reptiles with four tiipper-liko limbs and strong swimming tail. Flourished in the cretaceous. Mosasaurus, CUdastes. Sub Order III. OPIIIDIA. The snakes are distinguished from most lizards by the absence of limbs, and connected with this the similar verte- brae in which only trunk and caudals can be distinguished. The caudals lack ribs, but these are present and long in the trunk region, serving for locomotion and supporting the body on tlieir distal ends. Since there are legless li
. A manual of zoology. Zoology. fiOO GIIORDATA. Sub Order II. PYTHONOMORPHA. Large, extinct, extremely elon- gate reptiles with four tiipper-liko limbs and strong swimming tail. Flourished in the cretaceous. Mosasaurus, CUdastes. Sub Order III. OPIIIDIA. The snakes are distinguished from most lizards by the absence of limbs, and connected with this the similar verte- brae in which only trunk and caudals can be distinguished. The caudals lack ribs, but these are present and long in the trunk region, serving for locomotion and supporting the body on tlieir distal ends. Since there are legless lizards, it is further necessary to say that in the Ophidia the girdles and sternum are lost, only the Peropoda having remnants of the hinder appendages and pelvis, but these not connected with the vertebral column. Further distinctions exist in sense organs and jaws. The columella is indeed present, but tympanum and Eustachian tube are lacking. The eye- lids also seem to be wanting, but examination shows, in front of the cornea and separated from it by a lachrymal sac, a transparent membrane, com- posed of the fused eyelids (outer cornea). The apparatus of the jaws (figs. 619, 637) is remarkable for its great extensibility, which enables snakes to swallow animals larger than themselves, after coiling around them and crushing them. This extensibility is in part due to the fact that the bones of the lower jaw are bound together at the symphysis by elastic ligaments, in part to the freedom of motion of the bones of the upper jaw (excepting the small premaxillaries) and the j^alate. Further, the squamosal (Sg), quadrate {Q), and transversum (Tr) ai'e elongate and slender, the quadrate being widely separated by the squamosal from the skull, while the zygo- matic arch is entirely absent. The food is forced down the throat by hook-shaped Ijones on palatines and pterygoids. A wide distension of the stomach is rendered possible by the elasticity of its walls and the great mobility of the
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
