334 



ME. W. K. PAEKER ON THE STEUCTUEE AND 



Fig, 4. Horizontal section below the cranial cavity, exposing first arch, notochord, and 



investing mass. X 10 diameters. 

 Fig. 5. A subhorizontal section through the eyes and root of tongue. X 10 diameters. 

 Fig. 6. Part of the head, with outer part of cheek pared away. X 12 diameters. 

 Fig. 7. A section made through the plane of the hinder part of cranium. X 12 dia- 

 meters. 



Fig. 8. Part of same section. X 20 diameters. 

 Fig. 9. A similar section. X 26 diameters. 



Fig 10. Another subhorizontal section through the top of the first postoral cleft. X 20 

 diameters. 



PLATE XXX. 



Second Stage. — Emhi'yo Pig, 1 inch long. 

 Fig. 1. Section across the end of the snout. X 10 diameters. 



Fig. 2. Section through ethmoid region, root of tongue, and larynx, x 12 diameters. 

 Fig. 8. Section nearly in plane of the notochordal region, front view. X 10 diameters. 

 Fig. 4. A similar section, lower down, x 10 diameters. 



Fig. 6. Part of a similar section through apex of mandibular arch, front view, x 15 

 diameters. 



Fig. 6. A similar section through apex of next arch, front view, x 15 diameters. 

 Fig. 7. Another similar section through periotic capsule in plane of horizontal canal. 

 X 10 diameters. 



Third Stage. — Embryo Pig, 1^ inch long. 



Fig. 8. Part of a section through top of second postoral arch, corresponding with fig. C 



of second stage, front view. X 15 diameters. 

 Fig. 9. Side view of the three postoral arches. X 15 diameters. 



PLATE XXXI. 



Third Stage (continued). 



Fig. 1. 1st section through nasal region. X 7^ diameters. 



Fig. 2. 2nd section of same, x 7^ diameters. 



Fig. 2". Part of fig. 2. X 22^ diameters. 



Fig. 3. 3rd section of same. X 7| diameters. 



Fig. 3". Part of same section, x 22^ diameters. 



Fig. 4, 4th section of same, X 7-| diameters. 



Fig. 5. 5th section of same. X 7-^- diameters. 



Fig. 6. 6th section of same. X 7^ diameters. 



Fig. 6". Part of fig. 6. x 20 diameters. 



Fig. 7. 7th section of nasal region, x 7 ^ diameters. 



Fig. 7". Mandibular portion of same section, x 7^ diameters. 



