130 MR. W. it. BROOKS ON LUCIFER: 



and violent movements rendered the use of a camera impossible, they are not drawn 

 to a fixed scale. 



In all the Plates the capital reference letters are used to denote the same parts, as 

 follows : 



A. First antenna. 



A. I to A. G. The series of abdominal somites. 



An. Second antenna. 



C. Carapace. 



E. Compound eye. 



L. Labrum. 



M. Mandible. 



Mp. 1, Mp. 2, Mp. 3. The first, second, and third maxillipeds. 



MX. 1, MX. 2. The first and second maxillse. 



Oc. Ocellus. 



PL l-Pl. 6. The six pairs of abdominal appendages. 



Pr. 1-Pr. 4. The four pairs of thoracic limbs. 



R. Rostrum, 



T. l-T. 4. The four thoracic somites. 



T. Telson. (27. in Plate 3, fig. 26.) 



PLATE 1. 



The letter a in figs. 1 to 8, which were all drawn from the same egg, marks the 



same point in all. 



Fig. 1. An egg during the period of rest which follows the first period of segmenting 

 . activity. 



Fig. 2. The same egg at the beginning of the second period of segmenting activity, 

 five minutes after the stage shown in fig. 1. 



Fig. 3. The same egg five minutes later. One of the primary segments is beginning to 

 divide into two. 



Fig. 4. The same egg ten minutes later. One of the primary spherules is perfectly 

 divided into two, and the division of the other is less advanced. 



Fig. 5. The same egg five minutes later, and completely divided into four equal seg- 

 ments. This stage ends the second period of segmenting activity. 



Fig. 6. The same egg, fifteen minutes later, during the second period of rest. 



Fig. 7. The same egg, ten minutes later, entering upon the third period of activity. 



Fig. 8. The same egg, twenty-five minutes later, divided into eight equal spherules. 

 This stage ends the third period of activity. 



Fig. 9. Another egg during the third period of rest. 



Fig. 10. Another egg near the end of the fourth period of activity, and divided into 

 sixteen equal spherules, arranged around a central segmentation cavity. 



