194 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



the base, edges laminate, the lamime often somewhat irregular, 

 branching, but not very distinctly denticulate. Alre broad, with 

 nearly horizontal summits. 



The basis is calcareous, thin, not porous, its inner face deeply 

 grooved radially, the periphery being denticulate, with deep pits 

 for the basal septa of the parietes. 



The labrum (fig. GOc-) usually has three teeth-on each side. 



The palpus (fig. G0, c)- has an irregular longitudinal row of 

 pectinated bristles on the labrul face and two dense groups of spines 

 at the distal end. 



Mandible (fig. 01^) substantially as in B. crcnaius. 



FIG. 60. BALANUS HESPERIUS, ALBATROSS STATION :US."., BERING SEA. a, c, BOTH SIDES OF 



THE LAIUH'.M AND OF ONE PALPUS. l>, '27 Til SEGMENT OF CIRRUS VI. 



Maxilla (fig. 61&, c) is slightly notched under the two great spines, 

 there are nine spines below the upper pair in the type, seven in 

 another specimen, one of them stouter, as in B. Ixdanus. 



Cirri, first and second pairs injured in the type-specimen. The 

 posterior ramus of cirrus i has 9 or 10 segments; anterior segment 

 had been decidedly longer. Cirrus iii with the pedicel expanded as in 

 B. crenatus; posterior ramus of 12 segments two-thirds the length of 

 the anterior of 15 segments. The segments are densely bristly, with- 

 out any spinules or teeth. The posterior cirri have segments w T ith 

 three or four pairs of spines, the lower pair minute; the posterior 



