Morphological Studies. 781 



Description of Plates. 



Alphabetical references. 



ep epihlast, fh fore-brain, hh hind brain, Jo Jacobson's organ, 

 Jod duct of Jacobson's organ, n nose, np neuropore, oc optic vesicle, 

 oe olfactoiy epithelium, og olfactory ganglion, olan neural olfactory 

 ganglionic foundation, oil branch of olfactory nerve to nose, olll branch 

 of olfactory nerve to Jacobson's organ, olg lateral olfactory ganglion, 

 oil olfactory lobe, oo eye, p pigment, se sensory epithelium, s 6 smell- 

 bud, s gl smell-bud ganglion, sglc smell-bud ganglionic column, V tri- 

 geminus. 



All the figures are camera lucida drawings. 



The magnifications employed are A == 48, C = 120, D = 200, 

 F == 460 diameters. 



Plate XXXVI. 



Fig. 1. Longitudinal vertical section of head of a Tropidonotus em- 

 bryo to show Jacobson's organ {Jo) and its branch of the olfac- 

 tory nerve {ol II) Zeiss A. oc. 2. 



Fig. 2. A similar section of younger Tropidonotus embryo. Zeiss A. 

 oc. 2. 



Fig. 3. Sensory end-cells of a smell-bud of Jacobson's organ. Adult 

 T. natrix. Zeiss F. oc. 2. 



Fig. 4. Portion of sensory epithelium of Jacobson's organ from the 

 same embryo as Fig. 1. To show the ganglionic columns. Zeiss 

 F. oc. 2. 



Fig. 5. A similar column of Jacobson's organ of a younger snake 

 embryo. From the same embryo as fig. 6. Zeiss F. oc. 2. 



Fig. 6. Jacobson's organ and its innervation in a still younger stage 

 than figs. 1 and 2, showing the first formation of the smell-bud 

 ganglia. Zeiss C. oc. 2. 



Fig. 7. Jacobson's organ of an adult T. natrix in longitudinal section. 

 The figure shows the ganglionic columns (sglc), the terminal smell- 

 buds (sh) the branch of the olfactory nerve to Jacobson's organ 

 (olll) and a large amount of pigment (p). 



Fig. 8. Section of the central termination of the olfactory in a lizard 

 embryo. The figure shows the ganglionic basis of the olfactory 



