DIET ADAPTATIONS IN VARANUS NILOTICUS. 81 



that the pylorus glands are not only, as I formerly believed, 

 confined to the pyloric tract between the sphincter and the 

 valve, but that they also extend in front of the valve in 

 the strongly muscular portion of the ventricle. 



The mucosa of the pyloric tract is longitndinally plicated 

 and contains large aggregations of lencocytes. 



The muscular coat of the ventricle increases strongly in 

 thickness towards the posterior end. In the cardiac half it is 

 about half a millimeter in the moderately distended ventricle. 

 Four cm. from the sphincter its thickness is 2 mm. and one 

 cm. further back it is 3 mm. and has that thickness all the 

 way to the sphincter. which itself is 5 mm. in diameter in 

 this specimen. 



The muscularis mueosce consists, next to the glandular 

 surface, of circular fibres, tlien longitudinal fibres, although 

 less developed anteriorly than posteriorly, and finally, a se- 

 cond layer of circular fibres, more scattered than the others. 



Below this follows a submucosa consisting of a rather 

 loose connective tissue with scattered fibres. 



The powerful muscularis is chiefly made up of a thick 

 inner layer of circular muscles on the outer side of which 

 is found a longitudinal layer forming strong bands. 



In the pyloric tract between the sphincter and the valve 

 the muscularis is not so very thin, but the muscular bundles 

 seem to be more loosely connected and form less compact 

 lavers. The exteriör longitudinal muscles seem also to 

 be comparatively better developed than the inner circular 

 layer. 



The exteriör surface of the ventricle has a glistening 

 tendinous covering. Although this is not so concentrated 

 as in the crocodiles in which there is a tendinous centre on 

 either side of the gizzard-like ventricle, it is evident that 

 the tendinous covering in both instances serves the same 

 purpose viz. increasing the active power of the muscles. In 

 Varanus niloticus it seems as if the strongest portions of the 

 tendinous covering were situated on both sides a little in 

 front of the sphincter, — thus in a corresponding place as 

 the above mentioned centres in the crocodiles — and then 

 from there expanded forward, somewhat radiating all över 

 the ventricle. 



Arkiv för zoologi, Bd. \. * 



