44.2 BASHFORD DEAN. 
EXPLANATION OF PLATES 30—32, 
Illustrating Dr. Bashford Dean’s paper on “The Early 
Development of Amia.” 
PLATE 30. 
Figs. 1, 2, 4, 15, 19, and 20 drawn by Bashford Dean from the living 
eggs, the remaining figures from eggs hardened in alcoholic (50 per cent.) 
picro-sulphuric mixture, by Dr. Arnold Graf. x about 50. 
Fic. 1.—Living egg shortly before the appearance of the first cleavage 
furrow. About 4 hour after fertilisation. 
Fig. 2.—First cleavage ; it sharply separates the halves of the germ-disc, 
but extends no further marginally than its limits. 1 hour. 
Fic. 3.—Second cleavage, seen from above. 2 hours. 
Fic. 4.—Third cleavage; similar in marginal extension to the first and 
second. 3 hours. 
Fic. 5.—Fourth cleavage, 44 hours. 
Fic. 6.—Fifth cleavage, 53 hours. 
Fic. 7.—Sixth cleavage, 63 hours. 
Fic. 8.—Seventh cleavage, 74 hours. 
Fie. 9.—LHighth cleavage (early blastula), 83 hours. 
Fic. 10.—Early gastrula, 46 hours. 
Fie. 11.—Early gastrula, 48 hours. 
Fic. 12.—Gastrula, about 50 hours. 
Fic. 13.—Gastrula showing indented rim of blastopore at the dorsal lip. 
54 hours. 
Fic. 14.—Late gastrula, showing mode of closure of the blastopore ; the 
embryo’s appearance is faintly indicated in the light-coloured area imme- 
diately above the centre of the figure. 71 hours. 
Fic. 15.—Closure of the blastopore, and the appearance of the embryo. 
78 hours. 
Fic. 16.—Early embryo showing neural folds ; its length surrounds about 
185° of the egg’s circumference. About 93 hours. 
Fic. 17.—Early embryo, showing head region ; its length surrounds about 
195° of the egg’s circumference. Two somites present. 95 hours, 
