THE SESSILE BARNACLES. 343 



Plate 21. 



Figs. 1-lc. Balautts concavus Bronn. Typical form from British Rod Crag 

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



2. Baldiuis concavus gh/pfnpouia Pilsbry. Caloosahatchie IMiocone. 



Cotypo, Academy Natural Sciences of Philadelphia. I'age 102. 



3. Bahinus conrariis gli/ptopoma I'ilsbry. Miocene, Yorktown, Va. 



4. BakiHus rcfjalis Pilsbry. Interior view of rostrum and part of the 



basis of a cotype. Page 108. 



4c. Balanus rcgalis Pilsbry. Point Abreogos, Lower California. Co- 

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



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



Plate 22. 



Figs. 1-lc. Balanus concavus chcsapeakcnsis Pilsbry. Chesapeake Bay, Mary- 

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

 2, 2(7, 2/), 2c. Balanus concavus glyptopoma Pilsbry. Caloosahatchie River, 

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

 Sciences of Philadelphia. Page 102. 

 3-3c. Balanus concavus protcus 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-lrf. Balanus concavus paclficus 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 cburneus Gould. Smith's Creek, Potomac River, Mary- 

 land. Page 80. 

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

 yard. 

 3, 3a, 3b. Balanus iniprovisus Darwin. South Downs, England. Cat. No. 

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

 4. Balanus nmpliltrile pcruvianus 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, 3^, and 5 natural size. 



