PYTHON. 223 



bone, and five teeth in place : the mode of fixation of all these teeth 

 corresponds with that in the Boa constrictor. Their direction prevents 

 the escape of the prey in which they are once fixed ; while the separate 

 and independent movement of each half of both upper and lower jaw, 

 and of the dentigerous bones of the palate, allows of the different 

 series of teeth being successively withdrawn and implanted in a more 

 advanced position in the prey, which is thus gradually drawn into the 

 gullet, without the retaining force being unduly relaxed during any 

 part of the engulphing process. 



The teeth seem to be more numerous, or there is a greater 

 number in place at one time in the young than the old individuals of the 

 Python tigris ; I have counted fourteen superior maxillary and fifteen 

 premandibulars in place on each side of the mouth, in an individual of 

 this species six feet in length. 



The inner alveolar border is rather higher than the outer one in 

 the palatine bones. The pterygoid teeth are continued along the 

 middle of the inferior surface or towards the outer side of those bones, 

 whilst in the smaller Colubriform serpents they are placed on the 

 inner margin of the pterygoids. 



The teeth of both the Python and Boa consist of a body of firm 

 dentine coated by a layer of cement, which is extremely thin upon 

 the crown, but becomes thicker towards the expanded and attached 

 base of the tooth. The calcigerous tubes radiate according to the 

 ordinary course from the central pulp-cavity to the periphery of the 

 tooth : the superior and central tubes proceed in the axis of the tooth ; 

 those nearest to them incline outwards, deviating from the axis as 

 they recede from the point of the tooth, until they run at right angles 

 to the axis, which course they maintain throughout a great proportion 

 of the tooth ; hence a transverse section of the tooth, as magnified in 

 Plate 65 b, fig. J , exhibits the whole length of the calcigerous tubes. 

 Their primary curvature is slight, with the concavity directed towards 

 the base of the tooth : their secondary undulations are faint and 

 regular through seven-eighths of their course, but the tubes become 

 bent in stronger and less regular sinuous curves in the rest of their 

 extent, where, alone, they divide dichotomously, the terminal 

 branches frequently inosculating in loops, the convexity of which is 



