70 
BRITISH ENTOMOSTRACA. 
parts : beak, antennae, eye, brain, mouth, and masticatory 
organs, and part of the digestive canal. 
The thoracic and abdominal portions contain the 
remaining part of the alimentary canal, the heart, legs, 
and organs of generation. 
The beak is merely a prolongation of the hard covering 
of the head ; though it is asserted by Swammerdam to be 
the mouth of the animal, by means of which, being 
pointed, it sucks up its food. Both De Geer and 
Schceffer, however, pointed out the erroneous nature of 
this assertion; and later writers, such as Jurine and 
Straus, have still more clearly shown it to be wrong. At 
the extremity of this beak, and a little underneath it, we 
see two small projecting organs, which differ considerably 
in the two sexes ; these are the superior antennse (t. VIII, 
f. a, b, b ; t. X, f. la, 4 a). Schceffer, who is perhaps 
the first person who noticed these, considered them as 
palpi, by means of which the insect distinguished its 
food. Jurine calls them “ barbillons 55 in the female; but 
Straus considers them correctly as the true antennae of 
the animal, though he says they do not seem to possess 
any voluntary motion. In the female they are extremely 
small, and seem to have escaped Muller 5 s notice altogether. 
In the male they are much larger, and were considered 
by the last-mentioned author as the organs of generation 
(t. VI, f. 1 ; t. XII, f. 1 a). Jurine describes them very 
particularly in the jpulex, calls them “harpons, 55 and says, 
they occupy the place of the “ barbillons 55 of the female. 
They vary in the different species, and are each composed 
of several articulations. They seem to assist the first pair 
of feet in retaining hold of the female during the act of 
copulation. On each side, upon the base of the head, are 
inserted the large antennse. They consist each of a single 
joint at the base (t. VIII, f. a, a), dividing into two branches. 
This basal joint is slightly conical, generally of about the 
length of the head, and very flexible at its root, having a 
joint there, which unites it to the body, and facilitates its 
motions in every direction. 
