206 
ME. W. K. PAEKEE ON THE STRUCTURE AND 
Description of the Plates*. 
PLATE III. 
t' 
First Stage. — Embryo of Frog 2-3 lines long ; two days before and two days after 
hatching. 
Fig. 1. Front view of head before hatching, x 20 diameters. 
Fig. 2. Side view of the same, with ear-sac exposed. X 20 diameters. 
Fig. 3. Same as last, with facial arches, as well as ear-sacs, exposed. X 20 diameters. 
Fig. 4. Vertical section of head of the same. X 20 diameters. 
Fig. 5. Horizontal section of the same, immediately below the cranial cavity, x 20 
diameters. 
Fig. 6. A similar section taken a little lower down. X 20 diameters. 
Fig. 7. Another similar section, still lower down, and showing the floor of the mouth. 
X 20 diameters. 
Fig. 8. A transversely vertical section of fore part of face, seen from behind. X 20 
diameters. 
Fig. 9. A section, like fig. 5, of a more developed embryo (3 lines long). x!5 dia' 
meters. 
Second Stage . — Embryos 4 lines long, four or five days after hatching. 
Fig. 10. Side view of head, x 20 diameters. 
Fig. 11. Under view of the same. X 20 diameters. 
Fig. 12. Vertical section of the same. X 20 diameters. 
Fig. 13. Forepart of horizontal section of the same, from below, and showing the palate 
and inner nares. X 20 diameters. 
PLATE IV. 
Second Stage (continued). 
Fig. 1. Side view of head with sensory organs and facial arches exposed. X 20 dia- 
meters. 
Fig. 2. Horizontal section of head through eyeballs, ear-sacs, brain, and notochord. 
X 20 diameters. 
Fig. 3. Another horizontal section, dipping a little backwards, so as to expose the yelk- 
sac, below the notochord. X 20 diameters. 
* The hyaline cartilage, whether totally unossified or slightly affected by “ endostosis,” is coloured lilac, 
the endostosis being shown by a coarser marking than in that which is wholly unossified. The more solid 
bones, including all true “ ectostoses,” are coloured ochre-yellow, whilst the “ parostoses ” and fibrous mem- 
branes are not tinted. 
