THE SESSILE BARNACLES. 



325 



articular ridge in the middle. The occludent edge is broad and flat, 

 obliquely ridged in the lower part. Groups of intricately branching 

 crests at the two basal angles serve for the attachment of the de- 

 pressor muscles. The outside is regularly ridged transversely when 

 unworn and has one or more shallow radial impressed grooves. 



The tergum has a bisinuate scutal border; basal margin formed 

 of two subequal arcs, the posterior one occupied by the deeply cut 

 lateral depressor muscle crests, which in basal view are seen to be 

 intricately branching and pectinated. The exterior is seal brown, 

 with some lighter rays. The low growth-ridges are worn smooth 

 except along the carinal margin, where they are sharp and oblique. 



FIG. 97. CHTHAMALUS HEMBELI. NAPILI HARBOR, MAUI. a, MAXILLA. 1), MANDIBLE. 



C, ELEVENTH SEGMENT OF CIRRUS VI. d, PALPUS. , END OF THE PENIS. 



An old individual measures, carinorostral and lateral diameters 

 75 mm. ; height of carina, 41 mm. ; length of scutum, 45 mm. 



Carinorostral diameter, 76; lateral, 64 mm.; height of carina, 

 49 mm. 



Labrum has a simply concave edge, not toothed or spinose. 



The mandible has three strong teeth and a closely pectinated lower 

 point (fig. 976). 



The maxilla is very closely set with rather slender spines, not 

 varying much in size on the upper two-thirds, but shorter and nar- 

 rower on the lower third (fig. 97<z). 



The palpi are closely set with rather small spines near the distal end. 

 There is no group of long spines as in the other species (fig. 97t?). 



The cirri are densely pigmented, the pigment in dots, chiefly at 



the bases of the spines and along the carinal borders of the segments. 



4729 Bull. 93 i 



