076 A HISTORY OF RECENT CRUSTACEA 
CHAPTER XXIV 
TRIBE IV.—ASELLOTA 
THE second pair of antennz are elongate; the maxillipeds 
are furnished with an epipod, have the second joint pro- 
duced into a plate, and the ‘palp’ consisting of five dis- 
tinct joints. The first pleopods in the female are usually 
transformed into a single opercular plate, and in the 
male are variously modified; the four following pairs are 
branchial; the uropeds are terminal, or, if lateral, not 
remote from the apex of the pleon, one- or two-branched, 
or consisting of a single joint. There are two families, 
the Asellidz and Munnopsidee. 
Family 1.—Asellide. 
The mandibles have a denticulate cutting edge, a 
molar tubercle, and usually a three-jointed ‘palp.’ The 
limbs of the perezeon are prehensile or ambulatory, not 
specially modified for swimming. The marsupial pouch is 
formed of plates pertaining to the first four, or to the 
second, third, and fourth segments of the perzeon. Some 
twenty-five genera are included in this family, many of 
them exhibiting very striking peculiarities. 
Asellus, Geoffroy, 1762, shares with Mancasellus a cha- 
racter exceptional in the tribe to which it has given its 
name, in that the pleon in both sexes has the first pair of 
pleopods quite small, consisting in the female of two un- 
jointed oval plates, while the second pair are opercular, 
but not fused together in either sex. The female has but 
four, the male has five pairs of pleopods. The heart ex- 
tends from the pleon through the pereon. This genus 
belongs exclusively to fresh water. Asellus aquaticus 
