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 antennas (t. VIII, 

 f. A, B, h ; t. X, f. 1 a, 4 ci). 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" 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 Miiller'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 ft). Jurine describes them very 

 particularly in the /Wrr, calls them "harpons," and says, 

 they occupy the place of the "barbillons" 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 antenna 1 . They consist each of a single 

 joint at the base (t.VIII, f. A,f(), 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 e\erv direction 



