XXll EXPLANATION OF THE PLATES. 



Fig. 18. Tertiary or siiermatozoal cells. 



Fig. 19. Secondary cell of lobster seen from armed extremity, to show 

 the three setaj. 



Fig. 20. Primary cell, or coccum of testicle of Faf/urus hernhardas full 

 of secondary cells, c. Attachment. h. Free extremity, a. 

 Niiclens. 



Fig. 21. Primary seminal cell of Par/urus hernhanli<s fdling with se- 

 condary cells. As already described, these cells grow in pairs 

 from discs on the walls of the seminal tubes, and hang free 

 in the cavity of the tube. It has also been descril^ed how 

 the secondary cells are produced from the parent nucleus, 

 namely, by means of successive growths, each of which carries 

 off a fold of nucleus before it. 

 a. Disc from which the primary seminal cells grow. 

 hb. The discs on each side of it. 

 c c. The origins of the primary seminal cells. 



d. One of the primary cells cut oif. 



e. Nucleus of the primary cell in a state of activity ; it has just 



thrown off a series of young, marked 



f. In the diagram. 



g. Are several old walls of former growths. 

 h. Full extremity of primary cell. 



Fig. 22. A small portion of the testicle of Pagurus hernJiard'iis magni- 

 fied, showing the manner in which the cteca hang from the 

 walls of the seminal tube. 



Fig. 23. Small drop of seminal fluid of lobster, showing the secondary 

 cells before the armature had expanded. 



Fig. 24. Small drop of seminal fluid of lobster from vas deferens. 

 That part of the figure above a a, as seen under the micro- 

 scope, presents one dense mass of secondary cells floating 

 down towards &, where a few are seen separate. 



Fig. 25. A cfBcum from the testicle of Carcinus mceiias, showing a ger- 

 minal spot at its apex just being filled with secondary cells. 



Fig. 26. The germinal spot enlarged. 



REPRODUCTION OF LOST PARTS IN THE CRUSTACEA. 



Plates IX. XII. 

 Plate IX. page 471. 



Fig. 1 Represents the raw surface of the proximal or adherent portion 

 of the leg of Cancer pagunis, after the animal has thrown off 

 the distal portion. The figure rej^resents the parts of the 

 natural size, and oidy a few hours after the separation had 

 taken place. 



Fig. 2 Is a representation of the same part, after the young leg had 

 growii to some size. It will be observed that the cicatrix, 

 which was formed upon the raw surface a few hours after 



