443 
Natatory Legs. They are well developed on the four anterior 
thoracic segments; the fifth thoracic segment is reduced so that 
it — as in other Podoplea — looks as an abdominal segment, and 
it shall be mentioned separately below together with its rudimentary 
legs. In figs. 11—14 the left leg of the four anterior pairs are 
shown from in front; all these figures, together with fig. 4 and 
fig. 10, have been drawn with the same degree of enlargement 
(220 times), and a comparison of these figures will therefore show 
the relative size of nearly all appendages of the animal. The 
peduncles of the natatory legs are two-jointed, as long as or a little 
shorter than broad; their inner margin has no seta; a seta was very 
distinet on the outer edge of the second joint of the second and 
third pairs, but on the two other pairs it could not be discovered 
(perhaps it has been broken off). The ou1er ramus is three-jointed 
in all pairs; the inner ramus is two-jointed in the first pair (fig. 11) 
and three-jointed in the other pairs. The third pair have the 
longest rami (fig. 13); in the first pair they are considerably shorter 
than in the second; in the fourth pair (fig. 14) the inner ramus is 
about as long as the outer, but in the three other pairs the inner 
ramus is rather considerably shorter than the outer one. A very 
long flattened spine, which is serrated along the outer margin, is 
found on the end of both rami of the third and fourth pairs and 
on the outer ramus of the second pair; on the end of the outer 
rami of the three posterior pairs a short, flattened spine, serrated 
along the outer margin, is inserted outside the long serrated spine. 
Besides three sirailar, short, flattened spines, serrated along the outer 
margin, are inserted on the outer margin of the outer branch of the 
second and third pairs of legs: one of these spines originates from 
the side of the third joint, and the two other spines from the distal 
edge of the two proximal joints. The shape of the joints and the 
number of the natatory setæ on each joint can be studied on the 
figures; it may be added that these (generally pluraose) setæ are 
longer and thicker on the outer than on the inner ramus, but 
