THE SESSILE BARNACLES. 345 



PLATE 29. 



FIGS. 1, Ic. Balanus gregarius (Conrad). San Pablo formation, Salinas Val- 

 ley, Monterey County, California. Median longitudinal section 

 through the carinorostral axis, and external lateral view of the 

 same individual. Length, 198 mm. Property of the United 

 States Geological Survey. Page 126. 



PLATE 30. 

 Balanus nubilis Darwin. Page 131. 



FIGS. 1-lc. Straits of Juan de' Fuca, Washington. Cat. No. 4S014, U.S.N.M. 

 1, Inside of scutum ; la, group, natural size; lb, part of the basal 

 edge of the carina ; Ic, segment of basis, showing spongy struc- 

 ture of the lower layer. 



2, 2a. Puget Sound. Cat. No. 48015, U.S.N.M. Tergum and lateral view 



of wall, the latter natural size. A young specimen. 



3, 3. Admiralty Inlet, near Port Townsend, Washington. Natural size. 

 Valves of the same individual are shown enlarged in plate 31, 

 figs. 3, 3a. 



4. Group, Cat. No. 4669, U.S.N.M., the largest individual having 

 partly lost the outer lamina, exposing the parietal tubes. Four- 

 fifths natural size. 



PLATE 31. 



FIG. 1. Balanus aquila Pilsbry. Santa Barbara, California. Cat. No. 

 9432, U.S.N.M. Lateral view of a perfect individual. Page 127. 

 2. B. aquila. San Diego, California. Cat. No. 9434, U.S.N.M. In- 

 ternal view to show strongly bifid alse of the carina and lateral 

 compartment. 



3, 3fl. Balanus nubilis Darwin. Tergum and scutum of very deeply cor- 



roded specimen from Admiralty Inlet ; 1| natural size. Page 131. 

 4, 5. Balanus nubilis Darwin. Tergum and scutum of well-preserved 



individual, Cat. No. 48014, U.S.N.M., from the Straits of Juan de 



Fuca. 

 4a. Balanus aquila Pilsbry. Monterey Bay, California. Cat. No. 



32403, U.S.N.M. Lateral view of the type, seated upon a rock 



which is partly concealed by worm-tubes. Page 127. 



PLATE 32. 



FIGS. l-l/. Balanus flos Pilsbry. Monterey Bay, California. Cat. No. 32405, 

 U.S.N.M. Lateral and apical views, and opercular valves of the 

 type. Page 135. 



2-2c. Balanus aquila Pilsbry. Valves of the type individual figured on 

 plate 31, fig. 5. Reproduced from the Bulletin of the Bureau 

 of Fisheries, vol. 26, plates 8 and 9 ; drawn by Helen Winchester. 



Page 127. 



