M. E. Hesse on the Pranizze and Ancei. 409 
tached to a common peduncle. Besides the branchial feet, the 
sixth segment presents on each side, near its antero-lateral 
angles, a false foot with a very short basal joimt, and with two 
terminal lamine extended horizontally in the form of a caudal 
fin. In the young, the abdomen is generally nearly as broad 
as the thorax, and presents no constriction either at base or 
apex. 
Structure of the Pranizee at the period of their transformation 
into Ancei. 
After their attaining the form just described, the Pranize 
undergo little modification of form: the, antenne, thoracic feet, 
and abdomen scarcely change; but the head and thorax are 
subject to some modification. 
The head is remarkably small, distinct from the body, trian- 
gular in form, globular above, flattened below, and incurved at 
the apex. Seen from above, it appears to be clearly divided into 
three parts—namely, the extremity of the rostrum, the rostrum, 
and the forehead. The apex of the rostrum is conical and 
acuminated ; it is formed by two mandibles, which are pointed, 
denticulated within, and incurved. The rostrum is enlarged in 
the middle, and narrowed towards its junction with the forehead, 
from which it is separated by a straight raised line, the extre- 
mities of which reach the base of the antennee. The rostrum is 
traversed vertically by deep lines or grooves, indicating the union 
of five pieces; and besides these there are two lateral ones which 
embrace the former, and are soldered to them at the base, but 
free at the apex, which is pointed and recurved; from within 
these two lamine issue the styles with denticulated apices, which 
are seen at each side of the extremity of the rostrum. 
The antenne (already described) are inserted at the base of the 
rostrum, in a notch which presents a rounded process; this is 
the auditory tubercle: the skin covering its extremity presents a 
sort of very close network formed of crossing lines. 
The eyes are large and prominent, hemispherical, and com- 
posed of round facets; they are placed obliquely on the sides 
of the head. The neck presents three folds. 
Seen from beneath, the head presents the same threefold divi- 
sion: the apex has nothing remarkable about it; but the two 
other parts contain the buccal apparatus. The mouth is closed in 
front by the first pair of footjaws, consisting of the inner branch, 
which is lamellar, notched at the apex, and terminated by two 
blunt points furnished with hairs. These footjaws have no palpi ; 
their outer margins appear to be attached to the head in the 
manner of a hinge, as in the Ancei. The second and third pairs 
of footjaws, covered by those just described, form denticulated 
