146 BRITISH ENTOMOSTRACA. 



this organization is fitted for both swimming and walking, 

 the filaments assisting in the former, and the hooked claws 

 at the extremity aiding in this latter purpose, enabling 

 them to seize hold of the plants, &c. among whieh they 

 li\e, and thus walk from place to place. Latreille con- 

 siders these long filaments as acting, along with those of 

 the superior antennae, the part of respiratory organs. 



The mouth is situate in the inferior surface of the an- 

 terior lobe of the body, and consists of a lip, an inferior 

 lip, a pair of palpiferous mandibles, and two pairs of jaws. 

 The lip is composed of a large piece, shaped somewhat 

 like a hood, forming a projection which advances between 

 the two inferior antenna:', and is fixed to the body by four 

 long apophyses. The inferior lip is elongated, triangular, 

 and movcable; is articulated with the lip, and has at its 

 extremity two curved apophyses to articulate it with the 

 second pair of jaws. 



The mandible (t. XVIII, f. 1 d} is very large, and is 

 formed of two pieces. The larger, or mandible properly so 

 called, is terminated at its superior extremity by a point, and 

 at the lower or incisive extremity by five pretty strong teeth. 

 The other piece is in form of a palpus, which issues from 

 about the middle length of the proper mandible, and 

 consists of three joints provided with several set;r. The 

 first joint has near its base a very small branchial plate 

 terminated by five digitations. This palpiform part of 

 the inaudible is the second pair of feet of Jurine, the 

 barbillon of Miillcr; the use of \\hich, both agree, is to 

 cause a current of water towards the mouth, carrying 

 with it the particles destined for the animal's food. The 

 first pair of jaws (t. XVIII, f. 1 f) have for their base a 

 large square plate, furnished at anterior extremity with four 

 fingers, the superior of which is of two joints, the other 

 three having only one each, but all terminated by several 

 long hairs. From the external edge of this plate, forming 

 the base, arises a large, elongated, branchial plate (f. lr*), 

 which gives oil' from the superior crescent ic-shaped edge' 

 a row of nineteen long spines, arranged like the teeth of 



