100 



SKULL OF A 43-MM. HUMAN FETUS. 



Fig. 17. 



Fia. IS. 



Fig. 19 



Fio. 20. 



Fig. 21. 

 Fig. 22. 



Fia. 23. 



Fig. 24. 



Fig 25. 



branches, the internal carotid artery, and 

 the processus alaris of the temporal wing 

 of the sphenoid are seen. Model 14. XlO. 



Right otic capsule, medial surface, frank view, 

 showing connections with adjoining cartil- 

 ages and openings toward the cranial 

 cavity. Model 5. XlO. 



The space within the right otic capsule seen 

 from within, modeled as a solid; the surface 

 presented fits into the cavity shown in 

 figure 23. Openings toward the cranial 

 cavity are shown. Note the large volume 

 of this cavity in comparison with that of 

 the membranous labyrinth which fills it 

 (fig. 19). Compare also figures 21 and 22 

 in this respect. Model 6. XlO. 



Membranous labyrinth of right otic capsule 

 contained within the space shown in figure 

 18. Figures 17, 18, and 19 were all drawn 

 from approximately the same point of view, 

 so that an accurate idea may be gained of 

 the space contained within the otic cap- 

 sule and the membranous labyrinth within 

 that. Model 7. XlO. 



Right otic capsule, lateral surface, frank view, 

 with openings looking outward. The at- 

 tachments of the cartilage of Reichert and 

 of the short process of the incus are seen. 

 Model 5. XlO. 



The space within the right otic capsule, seen 

 from without, modeled as a solid; the open- 

 ings are indicated. Model 6. XlO. 



Membranous labyrinth of right otic capsule 

 contained within the space shown in figure 

 21. Figures 20, 21, and 22 were all drawn 

 from approximately the same point of view. 

 Model 7. XlO. 



Medial wall of right otic capsule, seen from 

 without, the lateral wall having been cut 

 away. The cutting of the capsular wall 

 was not done in quite the same way as in 

 the model shown in figure 15, so that the 

 cut edges do not fit together exactly. The 

 inner wall of the space is seen with the 

 endolymphatic and internal acoustic fora- 

 mina. Model 26. XlO. 



View from front of mass of cartilage (massa 

 angularis) partially inclosed by the semi- 

 circular canals of the right otic capsule. 

 Above is seen the superior canal leading 

 into the space for its ampulla and, farther 

 downward and to the right, into that for 

 the utriculus. To the left is the space for 

 the ampulla of the lateral canal and, farther 

 back, the lateral semicircular canal appears. 

 Model 15. XlO. 



View of same mass of cartilage shown in figure 

 24, but seen from below. The lateral semi- 

 circular canal is conspicuous to the left, 

 passing above into an enlargement for the 

 ampulla of this canal and for the utriculus, 

 with the beginning of the superior canal 

 above. Below, the lateral canal passes 

 medially into an enlargement for the 

 inferior extremity of the posterior canal and 

 for the crus commune. Model 15. XlO. 

 Views of the angular mass from other aspects 



are seen in other figures, as from without in 

 figures 20, 5, 6, and froru within in figure 15. 



Fig. 26. Right maxilla, palate, medial pterygoid plate 

 with hamular process, temporal wing, 

 sphenopalatine ganglion, and associated 

 nerves, seen directly from within. Cut 

 surface showing junction of temporal wing 

 with alar process is seen. Note the incisive 

 suture partially separating the maxilla 

 and premaxilla. Model 11. X12.5. 



Fig. 27. The same structures as those seen in figure 26 

 with the exception of the medial pterygoid 

 plate, seen from above. The relations of 

 the maxillary division of the trigeminal 

 nerve and its branches to the different 

 structures are shown. Model 11. X12.5. 



Fig. 28. Lateral aspect of the right palate bone and 

 medial pterygoid plate, with their invest- 

 ment of condensed mesenchyme. Model 

 18. X12.5. 



Fia. 29. The same structures seen in figures 26 and 27, 

 but viewed from below. The tooth gutter 

 of the maxilla and premaxilla is conspicuous 

 and the lower end of the incisive suture 

 appears. The zygomatio bone also is 

 shown. Compare with figure 30. Model 

 11. X12.5. 



Fig. 30. Condensed mesenchyme enveloping the right 

 maxilla, palate, and medial pterygoid 

 plate. The developing teeth are seen in 

 their gutter in the maxilla. (Compare with 

 figure 29 drawn from approximately the 

 same point of view.) The cartilaginous 

 hamular process is seen projecting from 

 the medial pterygoid lamina. Compare 

 also with figure 36, for developing teeth of 

 the right lower jaw. Model 25. X12.5. 



Fig. 31. Frank view of the right mandible, Meckel's 

 cartilage, and associated structures, seen 

 from within. The cartilaginous precursors 

 of the auditory ossicles are seen above, in 

 relation to the facial and chorda tympani 

 nerves. A glimpse of the squama tem- 

 poralis is given and also of the goniale. 

 Note the relations of the mandibular 

 division of the trigeminal nerve. Model 

 9. X12.5. 



Fig. 32. Lateral aspect of lower end of the right Meckel's 

 cartilage, showing especially the area 

 applied closely to the mandible, where 

 the cartilage is showing the changes pre- 

 liminary to ossification. (Compare with 

 figures 33 and 35.) Model 16. Xl'2.5. 



Fig. 33. Right mandible from same viewpoint as in 

 figure 31, showing the tooth gutter and 

 area of close apposition to the lower end 

 of Meckel's cartilage. Model 10. X12.5. 



Fig. 34. The same structures as those shown in figure 31 , 

 but the model was rotated somewhat 

 medially around its long axis. While pre- 

 senting all the structures from a new angle, 

 it shows especially the relation of the 

 nerves to the mandible. Model 9. X12.5. 



Fig. 35. View of right mandible with the model in the 

 same position as that shown in figure 34; 

 it is rotated so as to afford a good view of 

 the tooth gutter. Model 10. X12.5. 



