80 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



6 2 . Ribs of the parietes within all continuous with septa in the wall (pi. 40, fig. 4a). 

 c 1 . Spur short, near the basi-scutal angle of tergxim. 

 d l . Adductor ridge of scutum strongly developed, remote from the pit of the 



lateral depressor muscle. 



e 1 . Radii narrow, with smooth, oblique summits; walls smooth, white under a 

 yellowish epidermis; spur of tergum one-fourth the width of the basal 



margin or less B. improvisus, p. 84. 



e 2 . Radii rather wide; walls white or colored; spur wider. 

 /'. Spur of tergum about one-third the width of the basal margin; basis 

 conspicuously porous; diameter up to about 25 mm., usually much 



less B. arnphitrite, p. 89. 



f 2 . Spur nearly one-half the basal width; basis with but few pores; sheath 

 dark colored; diameter up to about 30 mm. Peru. 



B. peruvianus, p. 97. 



d 2 . Adductor ridge of scutum short, a pit below it (pi. 43, figs. 4, 6, 7); spur 

 of tergum very short, broad, and truncate; basis not porous. West coast 



of North America B. glandula, p. 178. 



d 3 . No adductor ridge in the scutum. 

 e 1 . Basis porous; walls smooth, fragile, dull red, freckled with white. West 



coast of South America B. pcecilus, p. 110. 



e 2 . Basis not porous; walls smooth or ribbed, white; opercular valves with 



strong articular ridges. Northern seas B. crenatus, p. 165. 



c 2 . Spur wide at the base, tapering distally, rather remote from the basiscutal 

 angle, and near the middle of the basal margin. Adductor ridge of scutum 

 close to the pit for the lateral depressor muscle. 

 d 1 . Opercular valves white, thin; adductor ridge of scutum weakly developed. 



California B. flos, p. 135. 



d 2 . Opercular valves buff, solid; adductor ridge of scutum strong. West Coast. 



B. nubilis, p. 131. 



NOTE. B regalis, p. 108, is not included in the above key, as its opercular valves are unknown. 



SERIES OP B. AMPHITRITE. 



BALANUS EBURNEUS Gould. 



Plate 24, figs. 1-lc, 2. 



1841. Balanus eburneus GOULD, Invertebrata of Massachusetts, p. 15, pi. 1, 



fig. 6. 



1854. Balanus eburneus Gould, DARWIN, Monograph, p. 248, pi. 5, figs. 4a-4d. 

 1874. Balanus eburneus Gould, VERRILL, Invertebrate Animals of Vineyard 



Sound, p. 285, in Report of Commissioner of Fish and Fisheries, p. 579. 

 1897. Balanus eburneus A. Gould, WELTNER, Verzeichnia recenter Cirripedien- 



arten, p. 2G6. 

 1911. Balanus eburneus Gould, SUMNER, Bull. Bur. of Fisheries, vol. 31, p. 129, 



302, 645, chart 84. 



Type-locality. Boston Bay, Massachusetts. 



Distribution. Massachusetts to the Caribbean coast of South Amer- 

 ica, low water to about 20 fathoms. 



The barnacle is obliquely conic or sometimes shortly cylindric, 

 smooth, with a very acutely ovate orifice. Parietes and opercular 

 valves white, covered with light yellow epidermis, the radii white, 

 without epidermis. 



