AND TEETH OP THE OPISTHOGLYPHA. 



307 



I had hoped to be able to obtain several specimens of both 

 Xenodon and Bispholidtcs, in order that a full study might be 

 made of the characters of the " poison apparatus " in these ■ 

 peculiar types. But in this I have been disappointed. I have 

 made some dissections, but it was impossible to obtain a good set 

 of serial sections. So I am unable to determine what further 

 questions might be raised by such a study, or how a complete 

 knowledge of the conditions exhibited by Xenodon and Dispho- 

 lidics might affect the general lines of my arguments. However, 

 I hope at some future date to work on these two genera, 

 comparing and contrasting them with the genera I have had the 

 opportunity of studying. 



Aglypha. 



Dendrophis pictus. 



The anatomy of the general dissection of the glands and teeth 

 of Dendrophis is shown in text-fig. 8. Of the tAvo glands in 

 the maxillary region the superior labial gland occupies the greater 

 area, while the so-called parotid gland is confined to a small space. 

 As will be seen, they are so intimately related that it would be 

 diliicult to distinguish one from the other but for the colour. 

 This fact struck earlier workers too. Leydig (1873), in his work 



Text-figure 8. 



/i9. els- 



Dendrophis pictus. Dissection of head from tlie right side. Letters as before. X 3. 



on Tropidonotus, described that the " superior maxillary gland 

 divides itself into two portions which are distinct in the form and 

 the colour of their follicles ; the inferior part is grey and the 

 principal part is of a yellowish colour, and the follicles are larger 

 than on the grey part." 



Evidently this yellowish portion becomes specialised to secrete 

 a. fluid different from that secreted by the rest of the gland ; and 

 we shall see later that this fluid becomes more and more im- 

 portant in the higher snakes as a weapon of defence, and that 

 the teeth become modified to allow of its more careful use. 



