Antennules. 
321 
most hemispherical projection over the eye. The ventral margin 
of the forehead is bilobed and continues vertically on each side as 
a small flap, covering the insertion of the antennules. The ven¬ 
tral margin of the head is deeply concave and passes into the 
large labrum. Just above the labrum is a projection for the 
attachment of the muscle of the labrum and a spine on each side. 
The labrum consists of two parts, the outer a broad and trian¬ 
gular projection, the inner smaller. The edge of the labral 
projection is smooth. 
The fornices are moderately broad (PI. XIV, Fig. 5.), cov¬ 
ering the base of the antennae. They extend to the anterior 
edge of the head, and disappear just before reaching the fore¬ 
head, which they join at the point where the triangular passes 
into the rectangular portion. Below the fornix, the head be¬ 
comes thin from side to side, being thinner than the breadth of 
the forehead, and very high ventro-dorsally. 
GENERAL MEASUREMENTS OE THE ANIMAL. 
G-reatest height. 0.875 mm. 
Greatest length. 1.06 mm. 
Perpendicular length from haft-organ .... 0.717 mm. 
Forehead. 0.105 mm. 
Diameter of boss over eye. 0.07 mm. 
Projection of boss. 0.027 mm. 
Length of setae on ventral edge... 0.010 mm. 
Triangular piece of labrum, length. 0.122 mm. 
Triangular piece of labrum, width. 0.105 mm. 
Diameter of eye. 0.052 mm. 
APPENDAGES OF THE HEAD. 
(A.) Antennules. 
PI. XIV, Figs. 4, 5. 
The antennules are very long, almost as long as the branches 
of the antennae, cylindrical, tapering slightly at the end. The 
antennule forms a gentle compound curve, greatest at the 
proximal end. It is much narrowed at the point of attachment. 
