AN UNDIVIDED WRIST 239 
eurinatus of S. I. Smith, who says that the basal joint of 
the first antenne is ‘furnished externally with a large 
lamellar process terminating anteriorly in an acute angle 
in front of the eye,’ a description ill-suited to the epithet 
rudimentary. 
Legion 3.—Monocarpinea. 
The wrist, or fifth joint of the second pair of trunk-legs, 
is not subdivided, and generally the chelz of this pair are 
larger than those of the first. 
Spence Bate arranges in this group eleven families— 
the Thalassocaride, Atyide, Pontoniide, Caricyphide, 
Acanthephyridz, Paleemonidee, Nematocarcinidz, Tropio- 
caridze, Stylodactylidee, Pasiphzide, Oodeopidee, among 
which the first differs from all the rest by having the first 
pair of trunk-legs simple, and the last differs from all the 
rest by having the second pair simple. ‘The Tropiocaridee 
do not seem to deserve a separate existence, without 
further consideration. 
family 1.—Thalassocaride. 
The first trunk-legs are simple, the second chelate. 
Three genera are assigned to the family, one of them, 
Diaphorépus, Spence Bate, 1838, founded on what ‘is 
evidently the immature condition of some undetermined 
form.’ 
Thalassocaris, Stimpson, 1860, takes the place of 
Regulus, Dana, 1852, the latter name being pre-occupied. 
The species as yet known belong to the Pacific, and are 
regarded as a link connecting the Pandalidee with the 
Paleemonidee. 
Family 2.—Atyide. 
The carapace is dorsally smooth, with flattened ros- 
trum ; the scale of the second antennz short. The man- 
dibles have a molar process and cutting edge, but no ‘ palp.’ 
The third maxillipeds are four-jointed and pediform. The 
first and second trunk-legs are chelate, with spoon-shaped 
fingers. The telson is flattened, truncate, 
