134 A HISTORY OF RECENT CRUSTACEA 
pairs of legs, are subdorsal in position and of small size. 
The pleon folds under the trunk. In the female it has 
five pairs of appendages, of which the first is rudimentary. 
This legion is divided into two families, the Dromidze 
and Homolidee, the characters of which are here accepted 
as laid down in Professor J. R. Hendersou’s Report on 
the Anomura of the Challenger. 
Family 1.—Dromide. 
The carapace is subglobular, rarely flattened. The 
eyes are retractile into well-defined orbits. The first an- 
tennz fold in special fossettes. The fifth and usually also 
the fourth pair of legs are short, subdorsal in position, 
and in general prehensile. The vasa deferentia of the 
male pass through the bases of the fifth pair of legs and 
form tubular prolongatioas. 
The family contains some ten genera, one of which is 
British. 
The species, Dr. Henderson says, inhabit shallow 
water and moderate depths. The majority protect the 
body by an ascidian, a sponge, or by one of the shells of 
a bivalve mollusc. Milne-Edwards says that of the four- 
teen pairs of branchiz! the last two spring from the last 
two segments of the trunk, which in the Brachyura in 
general never carry any. He regards two little lateral 
pieces intercalated between the sixth and seventh seg- 
ments of the pleon in Dromia as rudiments of the appen- 
dazes of the sixth segment, but that may be regarded 
rather as a pious opinion than an established fact. 
Dromia, Fabricius, 1798, almost monopolised the 
family until it was subdivided by Stimpson into six 
genera in 1858, this subdivision being grounded chiefly 
on the disposition of the sternal sulci in the female.? In 
} Branchiz are called pleurobranechis when attached to the pleura 
or sides of the segment, podobranchiz when attached to the first joint 
of the limb, arthrobranchiz when they spring from the interarticular 
membrane between the segment and the iimb. 
2 For the structure of these sulci and the correspondence of the ap- 
pendages on the pleon of the male, see the account in de Haan, Fauna 
Japonica, Crustacea, p. 103. 
