Description of lllustrations. 



The series of eggs, embryos and larvae of Necturus, from which the following descriptions and the 

 appended illustrations were made, were collected May I5th, 1903 and kept at a water temperature of 

 17" — 18 '' C. The illustrations are copied from the original water colored pictures which were made by 

 Mr. Leonard H. Wilder, under the direction of the senior author. It should be emphasized that the ages, 

 measurements and illustrations are all made from the living objects. 



Fig. I. (X 10.) 



Side view of egg i day 4 hrs. after deposition. The first cleavage groove has reached the lower 

 pole of the egg. Second grooves extend to level of the equator of the egg. 



Fig. 2. (X 10.) 



Side view of egg l day 8 hrs. after deposition. The second cleavage grooves have reached the 

 equator. The grooves of the third cleavage pass in meridional planes, but have not yet reached the equator. 



Fig. 3- (X 10.) 

 Side view of egg i day 12 hrs. old. Five cleavage grooves have reached lower pole, dividing lower 

 hemisphere into six segments. 



Fig. 4. (X 10.) 



Side view of egg i day 16 hrs, old. The greater number of cleavage grooves pass in meridional 

 planes, many are latitudinal and some nearly radial. The upper surface of the egg shows sixteen segments, 

 the lower nine. 



Fig. 5. (X 10.) 



Side view of es!;g i day 20 hrs. old. The upper surface of the egg shows some fifty segments, the 

 lower nine. 



Fig. 6. (X 10.) 



Side view of egg 2 days 2 lirs. old. The upper surface of the egg shows more than one hundred 

 segments, the lower twelve. 



Fig. 7. (X 10.) 



Side view of egg 2 days 7 hrs. old. The upper surface of egg shows about two hundred cells. 

 The lower portion is in about same stage as described in Fig. 6. 



Norraentafeln zur Entwicklungsgeschichte der Wirbeltiere. XI. X 



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