LIFE HISTORY OF DESMOGNATHUS FUSCA. 315 



ready for the immediate resumption of aerial respiration 

 (Whipple, '06). It is a significant fact, therefore, that at the 

 completion of metamorphosis this naso-labial apparatus is in 

 working order. 



The orbital glands lie ventral to the eyeball (or, Fig. 21, b 

 and d )and open along the depression between the inner surface of 

 the lower eyelid and the eyeball itself. They are tubular glands 

 and make their appearance simultaneously with the formation 

 of the fold which gives rise to the lower eyelid itself, shortly 

 before metamorphosis. 



Dim/- 



c J -. -..- 



FIG. 20. Dissection of adult Desmognathus fusca in which the skin is removed 

 from the right side of the head, the naso-labial glands being removed with it. 

 Drawing shews under surface of skin with glands in place. Cj, conjunctiva; I, labial 

 glands; 3-5 and 8-n indicate the enumeration of the naso-labial glands; nlm, cut 

 end of tubule which lies in the groove of the maxillary bone. Other designations as 

 in Fig. 19. 



In connection with the development of the orbital glands it 

 should here be noted that unlike all other Urodeles (so far as the 

 facts have been reported), Desmognathus has no naso-lacrimal 

 ducts. As these are present in so closely related and associated 

 forms as Spelerpes and Plethodon, as well as in the less closely 

 related lunged forms, their absence here has some significance 

 which demands further study of the comparative morphology 

 and the habits of this species. 



