350 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



PLATE 43. 



Balanus glandula Darwin. Page 178. 



FIGS. 1-lb. San Diego, California. Cat. No. 48002, U.S.N.M. 



2. San Diego, California. Cat. No. 11151, U.S.N.M. Rostrum. 

 3, 3o. San Diego, California. Cat. No. 48040, U.S.N.M. Exterior nearly 



perfectly preserved. 



4-4c. Nazan Bay, Atka. Cat. No. 4S001, U.S.N.M. Exterior and oper- 

 cular valves deeply corroded, the outline of the tergum much 

 changed thereby. 



5. Sitka, Alaska. Cat. No. 1231G, U.S.N.M. Group on shell of Mytilus. 



6, 6a. Unalaska. Opercular valves of crowded examples. 



7, 7a. Sitka. 



PLATE 44. 

 Balanus balanoides (Linnseus). Page 182. 



FIG. 1. Exmouth, England. Cat. No. 12156, U.S.N.M. Rostrum of a worn 

 specimen showing parietal pores and transverse septa. 



la, ~Lb. Lower and upper views of a perfect example of the same lot. 



2. Savin Rock, New Haven. Cat. No. 4791, U.S.N.M. Group growing 

 on a pile, showing transition from low-conic form (above) to the 

 cylindric form caused by crowding (below). One of the latter is 

 shown detached at A. 



3, 3a, Cumberland Gulf. Cat. No. 3294G, U.S.N.M. Cylindric and conic 



forms. 

 4. Loch Fyne, Scotland. Cat. No. 12150, U.S.N.M. Tubular, solitary 



form, supporting several conic individuals. 



5-56. New Haven, Connecticut. Cat. No. 48041, U.S.N.M. Patelliform 

 ribbed specimens growing on Mytilus, with scutum and tergum. 



6. New Haven, Connecticut. Cat. No. 32947, U.S.N.M. Tergum of a 



tubular individual. 



7-7(7. Savin Rock, New Haven. Cat. No. 32947, U.S.N.M. Individuals 

 and groups taken from a densely crowded colony. 



Figs. 1, 5d, 5b, G enlarged ; the others about natural size. 



PLATE 45. 



FIGS. 1-lc. Balanus balanoides, " var. a." Nahant, Massachusetts. No. 2051, 

 A.N.S.P. Terga and scuta. Page 186. 



2, 2. Balanas balanoides (Linnaeus). Nahant, Massachusetts. No. 2052, 

 A.N.S.P. Tergum and scutum of small, deeply corroded speci- 

 mens. Page 186. 

 3-3o. B. b. ealearalus Pilsbry. Cold Bay, Alaska. Cat. No. 32949, 

 U.S.N.M. Group of entire animals, natural size. Scutum, both 

 sides, and inner view of tergum. Page 188. 



4, 4a. B. b. calcaratus. Sitka, Alaska. No. 2058, A.N.S.P. Lateral and 



basal views of an extremely thick and solid individual, 19 mm. in 

 greatest diameter. The depression shown in tig. 4 is where a 

 specimen of B. crenatux sat. Page 188. 



4b, 4c. Tergum and scutum of same individual. 



