624 Studies in tfte Theory of Descent. 



in all the land Amphibia. This organ, lying in the 

 intermaxillary cavity, appears, whenever it occurs, 

 to produce a kind of birdlime, /". e. a very gluti- 

 nous secretion, which serves to attach the prey to 

 the rapidly protrusible tongue. Although this 

 secretion may perhaps also have another function, 

 from the absence of the intermaxillary gland in all 

 exclusively aquatic Amphibia, it follows that it 

 must be devoid of importance for, and inapplicable 

 to feeding in the water. The intermaxillary gland 

 is absent in all Perennibranchiata and Derotre- 

 mata which Wiedersheim has hitherto investi- 

 gated, viz. in Menobranchus, Proteus, Siren, 

 Cryptobranchus, Amphiuma, and Menopoma, all 

 of which are indeed without the cavity in which 

 the gland is situated in the Salamandrina, i. e. 

 the cavum inter ma xillare. 



Now in the Salamandrina the gland appears 

 at an early stage. It is possessed in a well- 

 developed state by the larvae both of species of 

 Triton and of Amblystoma, where indeed the 

 glandular structure completely fills the cavum 

 intermaxillare. 



Were the Axolotl a species retarded in phyletic 

 development, the presence of a gland which does 

 not occur in any other Perennibranchiata, and 

 which is only of use for life upon land, would be 

 quite inexplicable. 



The matter becomes still more enigmatical 

 through the fact that the gland, although present, 



