THE SESSILE BARNACLES. 97 



BALANUS AMPHITRITE INEXPECTATUS, new subspecies. 

 Plate 20, figs. 5 to be. 



A series of about 40 specimens from the Gulf of Califoniia, Cat. 

 No. 12.39S:, U.S.N.M.j the largest 15 mm. in diameter, was collected 

 by Dr. E. Palmer. They grew on oyster shells. The shape is low- 

 conic, with diamond-shaped orifice, with an even margin. The smooth 

 parietes are of a dull purplish-blue (Ranier blue) color, with many 

 indistinct, whitish^ radial lines, the radii white and drab, with sum- 

 mits parallel to the base. The interior is strongly costate. Basis 

 porous tlii'oughout, radially grooved inside. 



Scutum with the basal margin longer than the tergal; dull dark- 

 purplish, with a white band along the tergal margin, and an irregidar 

 whitish ray near the occludent margin. There are minute growth- 

 stria) and faint longitudinal scratches. The articular rib is very high 

 and prominent, terminating downward in a point. Adductor ridge 

 long and strong; helow it is a deep oblong pit, as if for a muscle- 

 insertion. There is a very small pit for the lateral depressor muscle. 

 The upper part of the valve is conspicuously roughened. 



Tergum white, flat externally, the rather broad spur-fasciole 

 defined by grooves. Spur wide, over one-third the width of the valve, 

 short, either rounded or truncate distally, separated from the basi- 

 scutal angle by less than half its own width. Crests for the depressor 

 muscles are strong and project below the margin. The inner face of 

 the valve is roughened. Articular ridge high, articular furrow wide 

 and rather deep. Scutal border ratlier broadly inflected. 



Possibly referable to the very inadequately described var. ohscurus 

 Darwin, which, from the aUeged distribution, I suspect to be merely 

 a color-form and not a race; yet as Darwin records no specimens of 

 amphitrite from the west coast of the Americas, it is not hkely that he 

 had the present race. 



BALANUS AMPHITRITE PERUVIANUS Piloory. 



Plate 24, fig. 4; plate 37, figs. 2-2c. 



1909. Balanus pcruvianus Pilsbry, Proc. U. S. Nat. Mua., vol. 37, p. 60, fig. 1, 

 pi. 10, figs. 1-4 (October 18). 



Cotypes.—Cnt. Nos. 38691 and 38692, U.S.N.M. 



Distrihution. — Salt creeks at La Palasada, near Tumbez, Peru, 

 growing on mangroves. 



General form conic, with flat or concave base and rather small 

 aperture; dirty pm-plish white or pale dull purple, radii usually 

 darker; very solid and strong. The parietes are smoothish, without 

 ribs, and only minutely roughened. The aperture is pentagonal, with 

 a strongly notched margin. Traces of a thin, pale straw-colored 



