PYTIIONIDiE. 59 



constrictor in the Hunterian Museum, whicli is thirteen feet nine 

 inches in length. The habit of attaching themselves to trees, 

 and holding on by the tail, their heads and bodies floating 

 listlessly on some sedgy river, is explained by the structure of the 

 tail. Dr. Meyer has minutely described the manner in which they 

 hook themselves on to a tree, which gives them the power of a 

 double fulcrum. The apparatus which gives this power is a spur 

 or nail on each side of the vent in the PytJwnida, in which the 

 anatomist discovered the element-s of an unguinal phalanx articu- 

 lated with another bone much stronger, which is concealed under 

 the skin. 



Following the arrangement of the Pythonidxs, adopted by Dr. J. 

 E. Gray in the Catalogue of the British Museum, we find : — 



I. Morelia, having a strong prehensile tail, distinct head, 

 truncate muzzle, crown of the head with small shield-like plates. 

 Of this genus there are two species. The Diamond Snake 

 {M. spilotes), a native of Australia, and of a bluish-black colour; 

 and the Carpet Snake {M. variegata), from Port Essington and 

 Swan River. It is whitish, with irregular black-edged olive 

 spots, and an oKve head, with two or three white spots in the 

 centre of the crown. 



II. Python, having the crown shielded to behind the eyes. 



Of this genus there are two species, which have sometimes 

 been referred to the Boas. The Pythons bear the same general 

 appearance. Upon their bodies is traced a sort of blackish- 

 brown chain, presenting nearly quadrangular links upon a clear 

 yellowish ground, extending from the nape of the neck to the 

 extremity of the tail. The suscephalous region is partly covered 

 by a large brownish-black spot. Upon each side of the head is a 

 black band, which frequently extends from the nostril, passing by 

 the eye, as far as, and up to., the commissures or corners of the lips. 



P. reticulatus, the Ular Sawad of the Malay countries, found 

 also in Burmah and Siam, has the four front upper labial plates 

 pitted ; the frontal plate simple ; the head has a narrow, longi- 

 tudinal, brown stripe. This is one of the most handsomely marked 

 species of the whole family, its body being covered with a gay 

 lacing of black and golden j^ellow. It is said to attain the great 

 length of thirty feet, and is stout in proportion. In its native wilds 



