Bull. U. S. B. F., 1909. 



Plate XLII. 



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FiG. I. — Right toothed forceps of lobster in seventh stage, seen from above, and drawn from, molted shell. Dental armature of jaw, 

 marked a, shown greatly enlarged in figure 3. 



Fig. 2. — Teeth from dactyl of lobster in fifth stage, showing multiple or bifurcate ducts of tegumental glands. 



Fig. 3. — Serrate margin of jaw in area marked a. figure i, embracing series i-ii, and showing spines pierced by the ducts of tegu- 

 mental glands. Cuticle only represented; enlarged about 170 times. Figures 1-3, from glycerine preparations and represented 

 in optical section. 



Figs. 4 and 5. — Armature of index or propodus of right toothed forceps of lobster in seventh stage, and after molting to the 

 eighth, as seen from under side, showing changes in spines of each period introduced at this molt, h, lock spine, and Sp, spur. 



