576 Proceedings of Royal Society of Edinburgh. [sess. 
so that at the end of the metamorphosis it consists of a single 
layer of flattened cells. The amesial attachment of the epiphysis 
becomes gradually less evident in these advanced stages owing to> 
this thinning of the roof of the thalamencephalon (see the list of 
embryos examined). Still in some cases the amesial communica- 
tion between the epiphysis and thalamencephalon is apparent even 
in these late stages, as a reference to fig. 8 will at once demonstrate. 
This is taken from a frog-tadpole (fifty-one days after fertilisation ; 
towards the end of the tadpole-stage). 
II. List op Embryos examined. 
The following is a list of the embryos which were examined in 
connection with this research : — 
(1) Frog, 
10 days, 
4 mm. long. 
Bilateral epiphysial recesses. 
(2) „ 
33 n 
4-5 „ 
33 33 33 
(3) „ 
5 3 5 3 
3 3 3 3 
33 33 33 
(L „ 
3 3 3 3 
3 3 3 3 
33 33 33 
(5) „ 
3 3 5 3 
5 
33 33 33 
Left 
(6) „ 
3 3 3 3 
4*5 „ 
(7) „ 
12 „ 
5*5 
33 33 33 
(8) „ 
3 3 3 3 
6 
33 33 33 
(9) „ 
21 „ 
12 
33 33 33 
(10) „ 
23 ,, 
12 
Mesial ,, ,, 
(11) „ 
25 „ 
13 
33 33 33 
(12) „ 
,, ,, 
13 
33 33 33 
(13) „ 
45 „ 
29 
Left ,, ,, 
(14) „ 
51 „ 
30 
33 33 33 
Bilateral , , , , 
(15) Toad, 
10 „ 
4*5 „ 
(16) „ 
3 3 3 3 
3 3 3 3 
Left ,, ,, 
(17) „ 
3 3 3 3 
5 
33 33 33 
(18) „ 
3 3 3 ? 
3 3 3 3 
33 33 33' 
(19) „ 
3 3 3 3 
3 3 3 3 
Mesial (?) ,, ,, 
(20) „ 
3 3 3 3 
„ (?) „ 
(21) „ 
13 ,, 
6-5 „ 
Left , , , , 
(22) „ 
16 „ 
8-5 „ 
33 33 33 
Mesial ,, ,, 
(23) „ 
3 3 3 3 
3 3 3 3 
(24) „ 
3 3 3 3 
3 3 3 3 
,, ,, ,, 
(25) „ 
17 „ 
3 3 3 3 
Left , , , , 
(26) „ 
20 „ 
10 
33 33 33 
(27) Newt, 
11 „ 
5-5 „ 
33 33 33 
(28) „ 
17 ,, 
9 
(?) 
(29) „ 
3 3 3 3 
3 3 3 3 
,, ,, , 
(30) „ 
3 3 3 3 
3 3 3 3 
Mesial , , , , 
(31) „ 
3 3 3 3 
3 3 3 3 
Left (?) 
(32) „ 
19 „ 
10 
33 33 33 
(33) „ 
20 „ 
33 3 3 
Mesial , , , , 
(34) „ 
33 ;j 
11 
Left ,, ,, 
(35) „ 
21 „ 
11 '5 
Mesial ,, ,, 
(36) „ 
30 , 
16 
Left ,, ,, 
(37) „ 
45 „ 
27 
Mesial ,, ,, 
