306 
In his monograph on the American barnacles Pilsbry (1916) 
points to systematic characters in Chtamalus, which possibly may 
be of value as regards an arranging of the species in larger groups 
within the genus. First he divides the species into two main groups 
according to the structure of the mandibles: in the stellatus- group 
the lower part of the mandible is comblike with a trispinose lower 
angle, whereas the Hembeli- group has the usual pectinate lower 
Fig. 51. Chtamalus antennatus from Port Hacking. a mandible, b maxilla, 
c distal segment of cirrus II. [X 68]. 
angle with no comblike part above it. Pilsbry with a quéstion- 
mark places Chtamalus antennatus in the Hembeli- group, not having 
had access to material of the species. The mandible (Fig. 51a) 
nevertheless at once indicates that Chtamalus antennatus belongs to 
the stellatus- group; the fourth tooth is small, and double, or we might 
speak of a fourth and fifth tooth; below these latter a comblike, 
although much shorter part than in Chtamalus stellatus, is devel- 
oped. The lower angle is armed with three rather large spines and 
a small fourth one, thus rather distinctly differing from Chtamalus 
stellatus. — In the maxilla the notch is more pronounced than 
in Chtamalus stellatus, but the difference is not very conspicuous. 
Cirrus I has 9 and 6 segments in the rami, cirrus II 6 seg¬ 
ments in both rami. In cirrus II the terminal segment of both 
rami has 4 or 5 pectinate spines without larger teeth below the 
pectinate part, whereas Pilsbry in Chtamalus stellatus only in the 
longer ramus found one serrate spine; moreover the rami of cir¬ 
rus II are of equal length and width in Chtamalus antennatus. — 
In the cirri III—VI the segments carry three pairs of spines on 
the anterior side, only in the two posterior cirri a very small fourth 
proximal pair may also be found. The numbers of spines are thus 
lower than in the nearly related Chtamalus stellatus. 
