4 INEZ L. WHIFFLE. 



along the ventral border of the horizontal groove into which the 

 naso-labial groove leads. The orifices associated with the 

 grooves are usually visible externally through a lens, since each 

 is situated in the middle of a little elevation. 



Seen in transverse section, that is, in a series of horizontal sec- 

 tions, through the head, the naso-labial groove appears as an in- 

 folding of the entire epidermis (Figs. 2, 3 and 4, gr\ the deeper 



nl. 



op 



FIG. 2. Horizontal section through head of adult Desinognathus fusca, X 2O - 

 ac, acinous glands of skin ; gr, cross-section of naso-labial groove ; int, intermaxil- 

 lary glands; men, M. constrictor naris ; nc, nasal capsule; nl, naso-labial glands; 

 /j, w/ 2 , nl y the first, second and third naso-labial glands respectively ; nip, tubules 

 of naso-labial glands within the premaxillary foramina; ns, external naris; ol, 

 olfactory nerve ; op, internal nasal branch of ophthalmic nerve. 



portion of which has a curved outline, while the outer portion 

 dips abruptly in, giving the groove in transverse section the ap- 

 pearance of the letter V. It is deeper and narrower near the 

 naris and becomes wider toward the edge of the lip. Underlying 

 the groove is a dense mass of connective tissue (Fig. 3, c] richly 

 supplied with blood vessels. 



In these horizontal sections the naso-labial glands (;//) are seen 

 to make a vertical descent through the epidermis and then to 

 curve sharply and extend in either a general mesial or lateral di- 

 rection beneath the skin and parallel with it. Although it is 



