168 ANCEID.E. 



ISOPODA. ANCEIDJE. 



ABERRANTIA. 



ANCEID.E. 



Praniziens. MILNE EDWARDS. 



Pranizidce. DANA. 



Pranizadce. VAN BENEDEN. 



Decempedes. LATREILLE. 

 (Males) Gnathides, GnatJtonii, Gnathionii. LEACH. 



Anceens. MILNE EDWARDS. 



(Females) Praniziens pro})- dites. MILNE EDWARDS 



Pranizidce. WHITE. DANA. 



THE head has the first (or more probably the first and 

 second) segments of the body fused with it ; it is very 

 large, and flattened, or dorsally concave in the males ; 

 quadrate or ovate, and of moderate size, in the females. 

 The antennas are small or of moderate length, nearly 

 equal, inserted widely apart, composed of a three-jointed 

 peduncle and an articulated flagellum. The mouth is 

 very anomalous in its structure, differing very greatly in 

 the adult from the young, as well as in the opposite 

 sexes of the same species. In the adult males the front 

 of the head is armed with a very large pair of porrected 

 mandibles ; in the early stages the mouth in both sexes 

 is suctorial in its character. The body is composed of 

 only five segments, of which the three posterior are 

 soldered together in the females, so as to form a large, 

 oval mass. There are only five pairs of slender, simple 

 legs. The pleon is of small size and narrow, but well 

 developed, consisting of six segments, of which the last 

 is small and triangular : each segment being provided on 

 its ventral surface with a pair of delicate, membranous, 

 biramous, squamiform appendages, which are entirely 

 free, and not covered by a larger anterior pair or oper- 

 culum. The terminal pair on each side form, with the 



