THE SESSILE BARNACLES. 343 



PLATE 21. 



FIGS. 1-lc. Balanus concavus Bronn. Typical form from British Red Crag 

 (Pliocene). Cat. No. 12058, U.S.N.M. Page 100. 



2. Balanus concavus glyptopoma Pilsbry. Caloosahatclne Pliocene. 



Cotype, Academy Natural Sciences of Philadelphia. Page 102. 



3. Balanus concavus glyptopoma Pilsbry. Miocene, Yorktown, Va. 



4. Balanus regalis Pilsbry. Interior view of rostrum and part of the 



basis of a cotype. Page 108. 



4a. Balanus regalis Pilsbry. Point Abreogos, Lower California. Co- 

 types. Cat. No. 43485, U.S.N.M. 



Figs 1ft, 2, 3, 4a about natural size. 



PLATE 22. 



FIGS. 1-lc. Balanus concavus chesapeakcnsis Pilsbry. Chesapeake Bay, Mary- 

 land, Miocene. Type, with tergum and scuta. Page 103. 

 2,2a,2b,2r. Balanus concavus glyptopoma, Pilsbry. Caloosahatchie River, 

 Florida, Pliocene. Scuta and tergum, cotype, Academy Natural 

 Sciences of Philadelphia. Page 102. 

 3-3c. Balanus concavus proteus Conrad. Virginia, Miocene. Scuta, ter- 

 gum, and apical view of typical examples, collected and labeled 

 by Conrad. Page 103. 

 Figs. 1 and 3c natural size. 



PLATE 23. 



FIGS. 1-1(7. Balanus concavus paciflcus Pilsbry. Lateral view, scuta and terga 

 of the type, San Diego, California. Cat. No. 32953, U.S.N.M. 



Page 104. 



2-2c. Balanus c. paciflcus form brevicalcar Pilsbry. Specimens from 

 Albatross station 2939. Page 337. 



PLATE 24. 



FIGS. 1-lc. Balanus eburncus Gould. Smith's Creek, Potomac River, Mary- 

 land. Page 80. 

 2. B. eburneus. Vineyard Sound, Massachusetts, off Martha's Vine- 

 yard. 



3, 3, 3b. Balanus improvises Darwin. South Downs, England. Cat. No. 



48009, U.S.N.M. Tergum and apical view. Page 84. 



4. Balanus amphitrite peruvianus Pilsbry. Rostrum with part of the 



basis of a paratype. Page 97. 



5-5d. Balanus improvisus Darwin. Quinnipiac River, below Grand Street 



Bridge. Cat. No. 48010, U.S.N.M. Group on an oyster, and oper- 



cular valves. Page 84. 



Figs 1, 2, 36, and 5 natural size. 



