290 CRUSTACEA. 
are entire, not granulate, and the lateral margins of the 
cephalothorax are slightly cristate. The under surface is also 
smooth and shining; only a few punctations are found on 
the smooth and shining abdomen, the middle joints of 
which are a little hairy. 
The anterior legs are elongate and slender, like 
those of Petrol. leptocheles and japonicus. They are somewhat 
unequal, the right being mostly the larger. The anterior 
margins of the meropodites are provided with a blunt tooth, 
that is again finely denticulate; the exterior margins of 
these joints by which they articulate with the carpopodi- 
tes, are armed inferiorly with a small acute tooth, both 
in the male and in the female. In the adult males the 
carpopodites are still alittle longer than the 
cephalothorax, but in younger specimens they are 
shorter than it. The carpopodites of the adult male, both 
of the right and of the left chelipede, are somewhat 
more than three times as long as broad, but in 
younger individuals they are comparatively less slender. 
The carpopodites of the anterior legs of Petrol. rufescens 
Heller, a species that occurs in the Red Sea and accor- 
ding to Hilgendorf also on the shores of Mocambique, 
are considerably broader and not yet twice as long as broad. 
The anterior margins of these joints are provided with 
three or four long, but rather low and little 
prominent teeth; in young specimens (Fig. 20) the 
first of these teeth is often sharp, but in older indi- 
viduals they are rather obtuse prominences and on the 
carpopodite of the larger or right chelipede of the largest 
male specimen (Fig. 2), the third tooth is so little deve- 
lopped, that I only observe two teeth, but the left car- 
popodite presents again four little prominent teeth. The 
posterior margin is armed, as in Petrol. inermis Heller and 
in hastatus Stimps., with a single sharp tooth at 
the distal end, which is not preceded by smal- 
ler ones. The hands are also elongate and slender; 
the larger is three times as long as measures its greatest 
INotes from the Leyden Museum, Vol. XV. 
