200 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



of which is large. There is a group of small spines above the lower 

 angle, as in other forms of the species. The third cirrus has very 

 few irregular spinules situated as in figure 615. The posterior cirri 

 have three pairs of spines on the segments, the lower pair very 

 minute, or sometimes wanting. 



This form differs from that of northern Asiatic waters by the 

 longer basal margin and finer external sculpture of the scutum, 

 the smooth parietes, and some reduction in the spines of the later 

 cirri. Whether these differential features will hold good when 

 the Japanese barnacle fauna is studied from adequate materials 

 remains to be determined. The characters are variable in B. hes- 

 perius. However, it has been thought desirable to signalize by 



FIG. 63. BALANUS HESPEKIDS NIPPONENSIS. SCDTUM AND 

 TEUGUM OF THE TYPE. 



name the presence of a modified form of the species in the much 

 warmer waters of Japan. 



METABALANUS, new submenus. 



Parietes and basis not porous; radii wanting; scutum having a 

 very weak articular and no adductor ridge; tergum w T ith a rather 

 long spur and no external furrow. Third cirri like the second, 

 armed with densely spinose areas and no small spinules. 



Type. Balanus Jioeklanus. 



The single species composing this group was formerly placed 

 by me in Hoek's section G of Balanus. It has been enumerated by 

 Doctor Hoek in his genus Hexelasma. The form of the mandible, 

 the ribbed interior of the wall, the overhanging lower edge of the 

 sheath, the long spur of the tergum, and especially the form and 

 chsetotaxy of the third cirri are all Balanid characters and make 

 it certain that the species is not a Hexelasma. Not having the 

 specimens at hand, I have been unable to examine the labrum, but 

 the description of the cirri is amplified below from the slide mounted 

 when I described the species. Whether the absence of radii is suffi- 

 cient to distinguish Metabalanus from Chirona is somewhat doubtful. 



