THE SESSILE BARNACLES. 



119 



The tergum (fig. 30^) is broader than that of B. spongicola, with 

 a shorter beak and broader spur. The basal margin is straight on 

 both sides of the spur, which makes angles with it on both sides. In 

 B. spongicola the basal margin slopes imperceptibly into the spur on 

 the carina! side. Crests for the depressor muscles well developed. 



The labrum has three teeth on each side (fig. 32/). Labial palpi 

 having a fringe of short spines along the upper margin, a distal 

 patch of long bristles, and an obhque row of long bristles on the 

 outer face (fig. d2d). The inner or labral face has a sigmoid Une 



Fig. 32. — Balanus calidus. a, median segment of cierus vi. 6, mandible, c, maxilla. 



d, OUTEE FACE OF PALPUS. C, SIXTH SEGMENT OF CIRKUS lU. /, LABRUM AND PALPUS. 



of short bristles, with larger ones, directed downward, above it 

 (fig. 32/). 



The mandible has four distinct teeth, the fifth concrescent with the 

 blunt lower point (fig. B2h). The maxilla has six spines between the 

 upper and lower pairs. 



Cirrus i has rami of 20 and 10 segments, the posterior ramus half as 

 long as the anterior, with moderately protuberant segments. Cirrus 

 ii has rami of 11 segments, the anterior ramus longer by about three 

 segments, though having the same number. Cirrus iii has rami of 

 11 and 10 segments, the anterior ramus longer by about three seg- 

 ments. The third to sixth segments of the anterior ramus have 

 teeth on the anterior border, with others, mainly trifid or multifid, 

 grouped in the anterior distal part of the segments (fig. 32e, sixth 

 segment) ; the eighth and ninth segments have very minute multifid 



