PLATE 5 



EXPLANATION OF FIGURES 



28 Details, as seen under slightly less magnification than was used in figure 

 27, of cell structure in region 2 of figure 26. 



29 Details, under the same magnification as used in figure 28, of cell structure 

 in region 3, figure 26. 



30 View of the ventral surface of the head of a 20-cm. alligator, showing the 

 two slit-like openings, mg' , of the mandibular or throat musk glands. 



31 Enlarged drawing of one of the openings shown in figure 30. 



32 Vertical section through the jaw of the embryo shown in figure 2. 



33 A somewhat more highly magnified section through the gland invagination 

 of an embryo of about the same size as, but slightly later development than, 

 the one represented in figure 32. 



34 Section through the mandibular gland of an embryo of about 4 to 5 cm. 

 length. 



35 Section through the wall of the mandibular gland of an alligator at about 

 the time of hatching; under moderately high magnification, to show cell structure. 



36 Surface view of a partially evaginated mandibular musk gland of a 1-meter 

 alligator. 



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