380 S. I. /Smith — Early Stages of the American Lobster. 



Figure 18. — Right maudible of tlie same speelmeu and seen in the same position. 

 Figure 19. — Outline of the mandibles in place as seen from beneath, from the earliest 



condition of the adult, enlarged 25 diameters. 

 Figure 20. — Left mandible of the same specimen, seen from the inside, enlarged 40 



diameters. 



Plate XVI. 



Figure 1 . — First maxilla of the right side seen from beneath, first stage, enlarged 40 

 diameters ; a, &, lobes of the endognathus ; c. exognathus. \a. tip of 

 the exognathus, enlarged 100 diameters. 



Figure 2. — Tip of the exognathus of the first maxilla of the right side, third stage, 

 enlarged 100 diameters. 



Figure 3. — First maxilla of the right side, earliest condition of the adult form, enlarged 

 20 diameters ; a, b, c, refer to the same parts as in figure 1. 



Figure 4. — Second maxilla of the right side seen from beneath, first stage, enlarged 

 40 diameters ; a, lobes of the endognathus ; b, exognathus ; c, epigna- 

 thus. 4a, tip of the exognathus, enlarged 100 diameters. 



Figure 5. — Second maxilla of the right side, earliest condition of the adult, enlarged 

 20 diameters ; a, b, c, refer to the same parts as in figure 4. 



Figure 6. — First maxilliped of the right side seen from beneath, first stage, enlarged 

 40 diameters ; a, endognathus ; b, mesognathus ; c, exognathus ; d, epig- 

 nathus. 6a, tip of mesognathus, enlarged 100 diameters. 66, one of the 

 plumose setfe from the margin of the exognathus, enlarged 200 diameters. 



Figure 7. — First maxilliped of the right side, third stage, enlarged 40 diameters; a, b, 

 c, d, refer to the same parts as in figure 6. 7a, tip of the mesognathus, 

 enlarged 100 diameters. 



Figure 8. — First maxilliped of the right side, earliest condition of the adult, enlarged 

 40 diameters; a, b, c, d, refer to the same parts as in figures 6 and 7. 



Figure 9. — Second maxilliped, first stage, enlarged 40 diameters ; a, exognathus ; b, 

 epignathus. 



Figure 10. — Epignathus of the second maxilliped, second stage, enlarged 40 diameters; 

 c, rudimentary branchial appendage 



Figure 11. — Same parts in the third stage, enlarged 40 diameters. 



Figure 12. — Second maxilliped of the right side, earliest condition of the adult, 

 enlarged 20 diameters ; a, exognathus ; b, epignathus ; c, rudimentary 

 branchial appendages. 



Figure 13. — Third (external) maxilliped of the right side, first stage, enlarged 25 diam- 

 eters ; a, exognathus ; b, epignathus ; c, rudimentary branchial append- 

 ages. 



Figure 14. — Same maxilliped, earliest condition of the adult, enlarged 10 diameters. 



Plate XVII. 



Figure 1. — Base of one of the legs of the second pair, first stage, enlarged 20 diam- 

 eters ; 6, epipodus ; c, rudimentary branchial appendages. 1 a, extremity 

 of the same leg, enlarged tlie same amount. 



Figure 2. — One of the legs of the second pair, second stage, enlarged 20 diameters; 

 a, exopodus ; b, epipodus ; c, branchial appendages. 2a, one of the plu- 

 mose setEe from terminal portion of the exopodus, enlarged 1 00 diameters. 



