306 PEOF, W. K. PARKER ON THE STRUCTURE AND 



PLATE LXIV. 



Fig. 1. Alligator mississijjensis {2nd Stage). Subhorizontal section of head (No. i), 



lowest, X 10 diam. 

 Fig. 2. The same (No. ii), X 10 diam. 

 Fig. 3. The same (No. lii), X 10 diam. 

 Fig. 4. The same (No. iv), highest, X 10 diam. 

 Fig. 5. Crococlilus jmlustris (3id Stage) : embryo, 2 inches long. Base of skull, upper 



view, X 6f diam. 

 Fig. 6. Part of same object, X 20 diam. 

 Fig. 7. Crococlilus pahtstris (3rd Stage): 2 J inches long. Palatal view of head, 



X 4| diam. 

 Fig. 8. The same object,. dissected, X 4| diam. 

 Fig. 9. The same, upper view of head, dissected, X 4f diam. 

 Fig. 10. The same, inner view of mandible, X 4§ diam. 

 Fig. 11. The same object, outer view, X 4| diam. 



PLATE LXV. 



Fig. 1. Crocodilus palustris (4th Stage) : embryo, 3i inches long. Chondrocranium 



of embryo, upper view, X 5^ diam. 

 Fig. 2. The same object, lower view, X 5^ diam. 

 Fig. 3. Part of same object, outspread, lower view, X 8 diam. 

 Fig. 4. Same embryo, visceral arches, obliquely external view, X 5^ diam. 

 Fig. 5. Alligator mississipensis (5th. Stage): larger embryos of this species, 4^ inches 



long. Palatal \iew of head, with lower arches removed, X 3 diam. 

 Fig. 6. The same, head in vertical section, X 4| diam. 

 Fig. 7. The same object, with the brain removed, X 4^ diam. 

 Fig. 8. The same head, outer view of chondrocranium, X 4| diam. 

 Fig. 9. The same head, upper view of hyobranchial plate, X 4| diam. 



PLATE LXVI. 

 Fig. 1. Alligator mississipensis (5th Stage): largest embryos. Dissected skull, side 



view, X 4^ diam. 

 Fig. 2. The same, inner view of mandible, X 4^ diam. 

 Fitr. 3. The same, lower view of skull, X 4i dium. 

 Fig. 4. The same, upper view of skuU, X 4^ diam. 

 Fig. 5. The same, transversely vertical section (1st) of head through external nostrils, 



X 8 diam. 



