224 Report of the Microscopical Section. [Sess. 
upper labrum springs. The antennz spring from the edge of 
this membrane, one on each side of the labrum. 
The Apus has two compound eyes, situate on the tergal 
aspect of the head. They are of a cuneiform shape, and are 
composed of several separate crystallines of a bluish-black 
colour. They appear like a bramble-berry cut in two longi- 
tudinally. They are covered by the outer layer of the cara- 
pace, which, as mentioned above, extends over the head, but 
at the parts covering the eyes this layer loses its brownish 
colour and is quite clear. 
The mouth is on the ventral aspect of the body, and is par- 
tially covered by the large upper lip or labrum mentioned 
above. The most prominent organs of the mouth are the 
mandibles, which have been already referred to, and the first 
pair of jaws (there are two pairs), consisting of two plates 
strongly ciliated and toothed. As the food of the Apus con- 
sists of the smaller entomostraca, these ciliated plates may be 
looked upon as strainers. 
The feet are very numerous, packed closely together, and 
extend from the mouth downwards along each side of the 
body, decreasing in size. The first pair of feet are situate 
immediately behind the mouth, and are for the purpose of 
locomotion; the others serve the purpose of respiration, and 
are called branchial feet. The general character of these 
branchial feet is a stem from which spring many finger-like 
appendages, strongly ciliated, a triangular plate finely ciliated, 
and another of an oval shape. As they descend the body these © 
PIES SI A ig TE BRIG 
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feet become modified, until at last they are merely rudimentary. _ 
The tenth branchial foot, however, deserves attention: it is 
modified so as to form a kind of ovarian pouch or capsule, and 
consists of two circular plates—the triangular and oval plates _ 
above mentioned modified to a circular form—the one a little © 
smaller than the other, bound together at one edge by a strong 
muscle, forming a hinge-like joint, enabling the smaller to be 
closed upon the larger like the lid of a capsule. In this cap- 
sule are contained the eggs, small dark-brown specks. In the 
one examined there were seven eggs. By a little delicate © 
manipulation the two plates can be separated, the smaller being _ 
folded back upon its hinge, thus enabling the internal structure 
to be examined. 
