78 CYAMID^l. 



labrum, rounded at the sides, but emarginate in front; 

 a pair of mandibles, bifid and denticulated at the tip, 

 but destitute of a palpus ; a first pair of maxillae, com- 

 posed of a single lobe ; a second pair of maxillae, much 

 smaller than and inserted between the first pair, upon a 

 common base, and each bearing a very minute two-pointed 

 palpus ; a labium, composed of two outer lobes and two 

 inner minute ones (representing the four maxillae), and 

 a large maxillary outer labium, furnished with a pair of 

 five-jointed palpi. 



Independent of the first articulation of the body, sol- 

 dered to the head, the animal consists of six flattened 

 segments, of which the middle ones are the broadest. 

 They are separated widely from each other at the sides, 

 and the last is terminated by a minute rudimental tail. 

 The segment attached to the head supports on its under- 

 side a pair of small legs, generally folded beneath the 

 body, composed of four joints, terminated by a subcheli- 

 form hand and a slender, curved finger. The following 

 segment of the body bears a large and powerful pair of 

 legs, although they possess one joint fewer than the 

 hinder pairs. The hand is broad and flattened, and the 

 finger curved and acute at the tip. The third and 

 fourth segments of the body are destitute of legs, but 

 their place is supplied by a pair of elongated, cylindrical, 

 branchial appendages, in some species being as long as 

 the legs themselves, generally turned over the back of the 

 animal. Sometimes these are simple, but in other cases 

 they are double, and at their base in the male is to 

 be observed one or two small corneous points. In the 

 female these two segments of the body bear two large 

 ovigerous scales, affixed at the base of the four branchial 

 appendages. The fifth, sixth, and seventh segments of 

 the body respectively bear a pair of legs nearly similar in 



