PLATE XXI 



Fig. 

 Fig. 



Fi£. 



Fig. i — 3. Balanus terebratus Darwin. 



Fig. 1. Labrum, with left-hand palpus; magnified 144 diameters. 



Fig. 2. Maxilla ; magnified 144 diameters. 



Fig- 3- Outer maxillae; magnified 144 diameters. 



Fig. 4 — 14. Balanus arcuatus n. sp. 



Fig. 4. Animal seen from above; magnified 10 diameters. 



5. Carino-lateral and lateral compartments, internal view; magnified 15 diameters. 



6. a and b, scutum and tergum, internal view; magnified 10 diameters. 

 c and d, scutum and tergum, external view; magnified 10 diameters. 



7. Transverse sections through compartments: a, not far from the orifice, b, halfway the 

 height, c, near the basis; magnified 10 diameters. 



Labrum, with left-hand palpus; magnified 144 diameters. 

 Mandible ; magnified 64 diameters. 



Maxilla, outer part with spines ; magnified 144 diameters. 

 Outer maxillae, right-hand outer lobe; magnified 144 diameters. 

 Third cirrus, fifth segment; magnified 206,5 diameters. 

 Fourth cirrus, fourth segment; magnified 206,5 diameters. 

 Sixth cirrus, tenth segment; magnified 206,5 diameters. 



15 — 20. Ba/anus quadrivittatus Darwin. 



Fig. 15. Shell seen from above; magnified 7,6 diameters. 



Fig. 16. a and b, scutum and tergum, internal view; magnified 7,6 diameters. 

 c and d, scutum and tergum, external view; magnified 7,6 diameters. 

 Fig. 17. Labrum; magnified 64 diameters. 

 Fig. 18. Mandible; magnified 64 diameters. 

 Fig. 19. Maxilla; magnified 64 diameters. 



Fig. 19*. Maxilla, edge with spines ; magnified 206,5 diameters. 

 Fig. 20. Outer maxillae; magnified 64 diameters. 



Fig. 



