NO. 1700. ON THE BARNACLES^ OF PERU—PILHBRY. 67 



now on Chilean territory. Besides the large form there is also on 

 the Peruvian coast a littoral form of B. psittacus^ which agrees better 

 with Molina's description than the large form hitherto considered 

 typical. 



Examples from Chincha Islands, " abundant on the shore rocks" 

 and Pescadores Islands, collected by R. E. Coker, are small, though 

 clearly adult. They measure 3.5 to 4.5 cm. high, 2.5 to 3.5 in basal 

 diameter. The shape is conic or vertical sided ; parietes irregularly 

 ribbed, radii rather wide. The orifice is ovate, or angular at the sides 

 and truncate at the rostral end. The color is dull whitish gray, some- 

 times partly dull pink. The parietes are ribbed lengthwise inside 

 below the sheath. The base is as flat as circumstances permit, and 

 either forms no part of the side walls, or is but slightly excavated. 



A group from the Chincha Islands, No. 38692 U.S.N.M., is figured, 

 of the natural size (pi. 16, fig. 4). 



The scutum is trapezoidal, the basi-tergal side parallel to the oc- 

 cludent and about as long as the basal margin. The tergal third is 

 bent at an angle of about 45° with the rest of the surface. The apical 

 third or fourth of the surface is smooth, the rest sculptured with 

 concentric lamellae and radial strise which crenulate the edges of the 

 lamelhe. Inside there is a deep and narrow articular groove and a 

 high acute articular ridge, which is confluent below with the ad- 

 ductor ridge. The latter continues nearly to the base, arching over a 

 cavity whirh peiietntfes nearly to the apex. The adductor muscle 

 scar is Avell marked (figs. 3, 4). 



The tergum is long and narrow, terminating in a long beak, from 

 one-third to one-fourth the length of the plate. The spur is long 

 and narrow, near the scutal margin. The longitudinal groove has its 

 sides closely folded together. The surface is sculptured otherwise like 

 the scutum. Inside, the articular ridge overrides the rib running 

 to the spur. Between this ridge and the carinal edge there is a short 

 narrow longitudinal ridge. The ridges and the space betAveen them 

 are jjurple. There are no crests for the depressor muscles (pi. 18, 

 figs. 1, 2, Chincha Islands). 



While it is related to B. tinfinnahulum by the porous Avails and 

 base, B. psitfaevs is very distinct by the narrow, long-beaked tergum 

 and the arched-over cavity of the scutum. The opercular plates, in 

 place, have the shape of a parrot's beak. 



BALANUS CONCAVUS Bronn. 



1838. Balanus concavus Bronn, Lethsea Geogiiostica, Vol. 2, p. 1155, pi. 36, 



fig. 12. 

 1854. Balanus concavus Bronu, Darwin, Monogrnpli ou the Cirrii>e(iia, 



Balanidfe, p. 235 (Peru, etc.). 



Locality. — Peru (Darwin, Balanidae, p. 236) ; Island of S. Lorenzo 

 in a recent elevated beach, 85 feet above the sea (Darwin). 



