ABBREVIATIONS 



b, basilar cells 

 bv, blood vessels 



c, corium 



eg, cloacal gland 



cl, cloaca 



cp, capsule 



ct, connective tissue 



d, duct 



dg, dorsal gland 



ds, dorsal scale 



ep, epidermis 



es, empty cell 



ev, evaginated part of gland 



g, gland 



gs, gs', gs", gland cells 



h, horny layer of epithelium 



h', central mass of horny layer 



I, lymphoid tissue 



lo, lobule of gland 



lu, lumen of gland 



m, muscle 



mc, Meckel's cartilage 



mg, mandibular gland 



mg', opening of mandibular gland 



na, neural arch 



nc, notochord 



nu, nucleus 



0, fat cell 



o', young fat cell 



od, oil drop 



]}, periderm 



pe, penis 



pg, pigmented granules 



pi, parallel lines, showing plane of 



section in figure 41 

 r, rib 



s, stratum germinativum 

 sc, spinal cord 

 st, strands of cells 



PLATE 1 



EXPLANATION OF FIGURES 



1 Two transverse rows of scales from the back of a 20-cm. alligator, to show 

 the location of the double row of dorsal glands, dg. The top of the figure is 

 cephalad, which shows that the glands are located in the anteromesial corners 

 of the lateral row of scales. Lateral to the four longitudinal rows of large dorsal 

 scales is shown, on each side, the edge of the small scales of the side and belly 

 of the alligator. X 3§. 



2 Lateral view of an alligator embryo of 25 mm. crown-rump measurement. 



3 Transverse section through the neck region of the embryo shown in figure 2, 

 to show, under law magnification, on the left side, the invagination of the epi- 

 dermis to form the dorsal gland, g. 



4 The gland, shown at g in figure 3, drawn under higher magnification to show 

 cell structure. 



5 Longitudinal section through the gland at a slightly later state of devel- 

 opment, drawn under moderately high magnification. 



6 Lateral view of an alligator embryo of about 13 cm. total length. 



7 Section through the dorsal gland and duct in the pelvic region of an embryo 

 of about 13 cm. total length. 



600 



