272 
margin is straight but for its foremost part which is a little con- 
vex in the region of the large prehensile antennae; the anterior 
part of the pupa has an evenly rounded outline. The pigmentation 
is feeble, and irregular. The nauplius-eye is very conspicuous, 
evidently with its typical three elements. Soon after the settling 
down of the pupa the eye becomes smaller, more concentrated, 
and its pigment quite black. 
Now the pupa becomes a little broader and attains somewhat 
rounded outlines, and the primordial valves appear. Their shape 
and size are characteristically different from other genera known. 
tergum is by far the smallest of the plates, and somewhat ap¬ 
proaches the outlines of a parallelogram, but for the rounded 
anterior part. Scutum is more than twice as large as tergum, 
approaching a trapezoid in shape, with a square basal margin just 
above (behind) the eye of the animal; the occludent margin is 
long and almost straight, the tergal, and carinal margins more 
rounded, thus somewhat concealing the trapezoidical shape of the 
entire plate. The carina is by far the longest plate of the capi- 
tulum; it covers more than two thirds of the dorsal side and ex- 
tends down to the foremost edge of the peduncular part of the 
body; the carina is also extraordinarily broad in comparison with 
other’ genera investigated. One more feature seems to be of inter- 
est, viz. the small intervals between the plates, which are more 
in accordance with Lepas, and strikingly differing from Mitella. 
The growth is to begin with characterized by an increase in 
the length of the peduncle, which also in young Megalasmae is 
comparatively well developed, and only later on again almost con- 
cealed by the progressive calcification of the plates (Fig. 30 c). 
During the first time of growth the primary valves are very ob- 
vious, but comparatively soon they seem somehow to disappear in 
this species. 
The main growth of the plates, and the main power of lime 
secretion in this species are bound to the zones of the capitulum 
between the primordial plates. The umbo of the tergum is almost 
quite apical, more pronounced in the older specimens than in the 
youngest stages. The carina has a basal umbo. The greatest in- 
terest is attached to the development of the scutum. In the prim¬ 
ordial valve a decidedly basal margin was evident; this latter is 
* 
