106 



BULLETIN 93^ UNITED STATES NATIONAL MUSEUM. 



Maxilla (fig. 256) with nine spines between the upper and lower 

 large pairs, the lower pair standing on a projection, in a Long Beach 

 individual, but this is scarcely noticeable in that from station 2939. 



The first cirrus in a specimen from Long Beach has 18 and 16 

 segments, the anterior ramus slightly longer, the posterior having 

 extremely protuberant segments. Chrus ii has subequal rami of 15 

 and 14 extremely protuberant segments (fig. 25a). Cirrus iii, anterior 

 ramus, has a few long "teeth" or rather short, spikelike spines on the 

 outer face of each segment near its anterior border. Those farther 

 from the anterior border are often twinned. By focusing down, some 

 excessively small spines, in groups of three or four, may be seen close 

 to the distal suture. The posterior ramus has no such armature. The 



Fig. 26.— Balanus concavus pacificus, station 2939. a, Anterior part op the 13th segment of 



THE FORWARD RAMUS OF CIRRUS HI. 6, MANDIBLE. C, ANTERIOR AND POSTERIOR PARTS OF THE 

 8th SEGMENT. 



inner faces of the segments of both rami bear long spines. The fourth 

 cirri have no teeth. Later cirri have segments with four pairs of 

 spines. 



In a larger example, from Albatross station 2939, the third cirrus 

 has its outer face set with curved, conic teeth on the anterior ramus 

 (fig. 26a), and with similar teeth mingled with bifid, trifid, or comb- 

 hke teeth (fig. 26c) on the posterior ramus, the teeth grouped near the 

 anterior and posterior distal angles of each segment. The fourth 

 cirrus has a few small erect spinelike teeth on the anterior distal 

 part of the lower segments of the anterior ramus. 



One of the large specimens from station 2939 has rather strong 

 rounded ribs in the lower half of the parietes, the upper half being 

 ribless and pink striped. Others of the same lot are typical in 

 sculpture (pi. 23, figs. 2-2c). 



