No. 2362. BARNACLES OF THE SAN JUAN ISLANDS— PI LSBRY 



113 



figs. 3, 6; Cat. No. 53812, U.S.N.M.). The young are not stellate, 

 with strong corrugation and small oriiice, but steep-walled with open 

 orifice and walls but little corrugated. These unusual forms of 

 cariosus are readily recognized by the shape and sculpture of the 

 opercular valves. 



BALANUS HESPERIUS LAEVIDOMUS Pilsbry. 



Friday Harbor (Cat. No. 53809, U.S.N.M., 10 specimens). It is 

 easily distinguished from the following species by the rather fragile 

 walls, which are not ribbed. 



BALANUS ENGBERGI, new species. 



Plate 20, figs. 4, 5. 

 Type.— Cat. No. 53801, U.S.N.M., from Olga, Washington, col- 

 lected by Dr. C. C. Engberg. 



Fig. 1. — Balanus exgbergi. 



External and internal views of the tergcm, a, and 

 of the scutum, b. 



The barnacle is rather small, conic, grayish white, strongly ribbed, 

 with a very small, shortly oval orifice, and partly covered with a very 

 thin and pale cuticle, in large part fugacious. The compartments are 

 not porose. The basis is calcareous, not porose. The opercular valves 

 have the general shape of those of Balanus crenatus. 



Greatest basal diameter of type, 14 mm. ; altitude 7.3 mm. ; length 

 of orifice, 2.5 mm. 



The scutum (fig. lb) is shaped like that of Balanus hesperius. The 

 tergal border is somewhat longer than the basal; the latter convex. 

 The occludent border has a series of regular short, oblique ridges. 

 The exterior is somewhat concave between the apex and base; quite 

 convex between occludent and tergal margins. It is closely and regu- 

 larly sculptured with high ribs, sloping downward; each alternate 

 rib continued in the short ridges of the occludent edge. It is dis- 

 tinctly, finely, and closely striate from apex to base. Inside there is 

 a rather strong articular ridge, but no adductor ridge. The pit of 

 the adductor muscle and the very small pit of the lateral depressor 

 are deeply sunken. 



27177— 21— Proc.N.M. vol.59 S 



