210 
ME. W. K. PAEKEE ON THE STEUCTUEE AND 
Fig. 13. Eighth Stage. — Middle-ear chain, with fenestra ovalis and part of auditory 
capsule, the “ stapes ” partly displaced. X 30 diameters. 
Fig. 14. Part of middle-ear chain (9th Stage) with medio-stapedial and stapedial cut 
through. X 30 diameters. 
Fig. 15. Section through “stapedial plate,” “fenestra ovalis,” and exoccipital and opis- 
thotic edges of the “ fenestral fossa” (old Frog). X 12 diameters. 
Fig. 16. Part of the skull of an adult Frog, with stapedial plate removed to show 
“fenestra ovalis” and “fenestral fossa.” X 12 diameters. 
PLATE VIII. 
Seventh Stage (continued). 
Fig. 1. Upper view of skull of young Frog with right mandible attached, and hyoid 
cornua cut through. X 12 diameters. 
Fig. 2. The same, lower view. X 12 diameters. 
Fig. 3. Part of fig. 1, suspensorium and auditory capsule. X 24 diameters. 
Fig. 4. Part of fig. 2, ditto. X 24 diameters. 
Fig. 5. Distal part of Meckel’s cartilage ( mk .) with dentary plate ( d .) still distinct. 
X 45 diameters. 
Eighth Stage. — Frogs of l,s£ early Summer. 
Fig. 6. Fore part of Meckel’s cartilage (ossified) with part of “ dentary” and “ articulare.” 
X 45 diameters. 
Ninth Stage. — Frogs of ls£ autumn. 
Fig. 7. Upper view of skull of a young Frog examined towards the end of the 1st 
summer; right mandible removed, x diameters. 
Fig. 7°. Part of the same, showing right suspensorium and auditory region, x 15 dia- 
meters. 
Fig. 8. The same skull, seen from below. X 7| diameters. 
Fig. 8". Part of fig. 8, showing lower view of suspensorium and auditory region, x 15 
diameters. 
Fig. 9. Tenth Stage. — Side view of auditory region of adult Frog with semicircular 
canals exposed and parts of middle ear displayed. X 7^ diameters. 
Fig. 10. Tenth Stage. — Section showing “fenestra ovalis” and “stapedial plate” from 
within. X 12 diameters. 
PLATE IX. 
Tenth Stage. — Old Frogs. 
Fig. 1. Upper view of skull of adult Frog with all the bones in situ. X 4 diameters. 
Fig. 2. Lower view of the same. X 4 diameters. 
