68 PROVEEUINGH OF THE NATIONAL MUSEUM. vol.37. 



The barnacle is conical, orifice rather small, radii narrow. Surface 

 generally smooth; color dull reddish-purple with whitish or darker 

 rays, pale rose-pink with white rays, or wholly white. Diameter of 

 the largest Peruvian (fossil) specimens about 4 cm. Recent ex- 

 amples are smaller, often about 15-20 mm. in diameter. 



The scuta are striated longitudinally, beading or denticulating the 

 transverse costulse. Articular ridge rather small; adductor ridge 

 usually very prominent. 



Terga very slightly beaked. There is a longitudinal furrow, usu- 

 ally deep, with the edges folded in and touching, extending doAvn to 

 the spur. 



This species may be distinguished from B. amphitrite by the longi- 

 tudinal striation of the scuta. 



BALANUS L.ffiVIS NITIDUS Darwin. 



Plate 17 ; plate 19, figs. 5-9. 



1854. Balanus Icevis Bruguiere var. nUidiis Darwin, Monograph on the 

 Cirripedia, Kalauida>, p. 227, pi. 4, fig. 2 (Chili, Peru, California). 



Loeality. — Arica, on the gastropod Coneholepas peruviana Jja- 

 marck; San Lorenzo Island, on i3ebbles at low tide (Dr. W. H. Jones, 

 U. S. Navy) ; Peru, on Coneholepas (coll. Acad. Nat. Sci. Phila.). 



The barnacle is nude, not covered with a cuticle, conic, white or pale 

 purple, or marked with purple lines near the summit; smoothish, 

 with very narrow radii. Orifice small, ovate or trapezoidal, with an 

 even, not toothed, margin. The parietes and calcareous base are 

 porous; the purple lines often visible near the summit being caused 

 by a purple calcareous filling of the parietal pores. The size varies 

 from a carino-rostral diameter of 8 to 10 mm., the height being about 

 the same, or in large crow^led groups they may become higher. 



The scutum is triangular, the basal and tergal margins of about 

 equal length. Surface covered with a yelloAv cuticle, to which re- 

 mains of old cuticle generally adhere; sculptured with fine transverse 

 riblets and having one or two deep longitudinal furrows. Inside, the 

 articular groove is narrow and deep, the articular ridge high and 

 strong, projecting in a point below. The adductor ridge is massive 

 and strong. The pit for the insertion of the lateral depressor muscle 

 is very deej), passing almost or quite through the calcareous layer of 

 the plate (figs. 6, 8, 9). 



The tergum has a broad spur, truncated at the end and nearly half 

 as wide as the whole plate. The longitudinal furrow is wide, with 

 the edges narrowly folded in. Surface elsewhere finely costulate 

 parallel to the basal margin. Inside there is a moderate articular 

 furrow and strong articular ridge. The crests for the depressor 

 muscles are strongly developed (figs. 5, 7). 



