WHITMAN AND EVCLESHYVMER: 
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on 
No 
EXPLANATION OF PLATE XVIII. 
All figures, excepting 8, 14, 17, and 20, drawn from living eggs. The numerals 
affixed to the cleavage grooves give the time in hours and minutes at which the 
grooves reach the points indicated by the dotted lines. The egg shown in 
Figs. 3-5 remained in a constant position. 
Figures 9-20 are so arranged that the first cleavage groove has always the same 
position. 
Fic. 1. Unsegmented eggs attached to grass. Natural size. 
Fic. 2. Profile view of the unsegmented egg, showing natural color of the 
egg and the villi by which it is attached. Made by J. Nomura. X Is. 
Fic. 3. Profile view of the egg 3 hrs.°23 min. after deposition, showing 
position and extent of the first vertical groove. X 14. 
Fic. 4. Profile view of same egg at 4 hrs. 19 min. The second verticals 
have extended slightly beyond the margin of the calotte. X 14. 
Fic. 5. Profile view of the same egg at 5 hrs. ro min., showing the position 
and extent of the first three sets of verticals. X 14. 
Fic. 6. Profile view of the same egg ‘at 6 hrs. 20 min., after the appearance 
of the circular groove. X 14. 
Fic. 7. Profile view of same egg at 7 hrs. 23 min. The fourth vertical 
cleavage is in progress. X 14. 
Fic. 8. Profile view of same egg at 8 hrs. 25 min., showing additional 
circular grooves, one set within, the other without, the first circular groove. 
X 14. 
Fic. 9. Showing a case in which the calotte is unequally divided by the first 
groove. X 13. 
FIGS. 10, 11, 12. Views of the upper pole, showing variations occasionally 
observed in the position of the second verticals. X 13. 
Fic. 13. View of the upper pole, showing variation in position of one of the 
third verticals. X 14. 
Fic. 14. View of the lower pole of same egg. X 13. 
Fic. 15. View of the upper pole, showing another variation in the position of 
the third verticals. X 13. 
Fic. 16. View of the upper pole, showing a variation in the position of the 
grooves of the first circular cleavage. X 13. 
Fic. 17. View of the lower pole of the same egg, showing points at which the 
second verticals terminate. X 13. 
Fic. 18. View of the upper pole, showing a broken circular groove. X 13. 
Fic. 19. View of the upper pole of an egg in a stage somewhat later than the 
one shown in Fig. 8. X 13. 
Fic. 20. View of the lower pole of same egg. X 13. 
