320 



BULLETIN 03^ UNITED STATES NATIONAL MUSEUM. 



prominent but not reflexed over the scutal margin. Spur extremely 

 short and broad. Basal margin straight. Crests for the depressor 

 muscle are weak. 



The free apices of both scutum and tergum are unusually long in 

 unworn specimens. If eroded, the outlines of the valves would be 

 considerably altered. The specimens were preserved dry, and I have 

 not examined the internal organs. 



This seems to be a strongly individualized species. Unv^orn ex- 

 amples may be recognized readily by the external furrow of the 

 tergum. The shape of the tergum and the small development of 

 the articular ridge in both tergum and scutum are also characteristic. 

 The external sculpture of the opercular "valves is much, finer and 

 closer than in C . anisopoTna. 



There is a very slight difference in the size of the opercular valves 

 of the two sides, at least in the individuals I have particularly 

 examined, but this is hardly noticeable unless the cleaned valves 

 are laid side by side. 



CHTHAMALUS IMPERATRK, new species. 

 Plato 75, figs. 1 to Ic. 



Type.— Cat. No. 48200, U.S.N.M. 

 Distribution. — Panama, on stones. G. B. Adams. 

 The barnacle is conic, depressed, spreading, the slopes even and 

 showing waved gray lines etched into low relief on the surface; 



when unworn it is set with small 

 granules, or in the early stages of 

 growth it is smooth. The orifice 

 is large and ovate; ala? broad, 

 with horizontal summits. Sutu- 

 ral edges smooth ; radii not differ- 

 entiated. The compartments are 

 moderately thick. The interior 

 of wall and valves is dull-violet 

 black or blue-violet black. The 

 basal edges of the wall are rough- 

 ened by some scattered tubercles, 

 or sometimes rather close, fine rugosites and asperities. There is no 

 trace of an ingrowing ledge. The sheath is very short (pi. 75, figs. 

 1, 1«, Ic, interior or rostrolateral, lateral, and carinal compartments). 

 Diameter, 14 mm. ; height, 3 mm. 

 Diameter, 13 mm. ; height, 2.5 mm. 



The opercular valves are thick, deeply eroded in adults, and are 

 colored inside like the wall. The scutum is of the usual triangular 

 shape, about twice as wide as high. The tergal border is very thiclc. 

 The articular rib is not very pi-ominent; articular furrow forms a 



Fig. 94. — Chthamalus imperatuix. 

 scutdm of an unworn individual, to 

 show the strauiht tercial border ; 

 length, 2.6 mm. 



