44 DR. J. G. DE MAN ON A NEW [ Jan. 20, 
scarcely reaching to the level of the mesial crescentic portion of 
the cervical suture, and i distinctly curves inwards on to the 
upper surface of the carapace. The orbits have the same form 
in both species, but in P. africanwm the incision that separates 
the extraorbital tooth from their lower margin is deep, much 
deeper than in the new species, so that in the former the outer 
angle of the orbits strongly projects beyond this margin. 
In P. africanum the transverse furrow, limiting off the sub- 
hepatic region from the branchial floor, is bordered by a row of 
small granules, the subhepatic area is covered with prominent 
rugosities and | granules ; in our new species the latter appears 
almost smooth, and the row of granules is also less distinct. The 
rugosities on the inflected portion of the cephalothorax and on 
the outer part of the pterygostomian regions are also much less 
distinct in the species from Upper Guinea than in P. africanum. 
The outer foot-jaws have the same form and characters in both 
species, and the furrow on the ischium-joint runs in both a little 
closer to the internal than to the outer margin of this joint. 
The type of P. africanwm is a female, the abdomen of which 
has not yet obtained its full development and size. The sternum 
of P. latidactylwm is smooth, punctate, and in both species a 
transverse furrow unites the postero-external angles of the buccal 
frame. The male abdomen (PI. IX. fig. 4) somewhat resembles 
that of P. consobrinum de M. (Notes Leyden Museum, 1899, 
pl. 10. fig. 10,2). The lateral margins are slightly concave. The 
terminal joint has about the same length as the penultimate; it 
is triangular, rather pointed at the tip, not rounded like that of 
P. consobrinum; the lateral margins are very slightly arcuate 
posteriorly, nearly straight towards the tip. The posterior margin 
of the penultimate joint is a little broader than the anterior ; the 
lateral margins, slightly convex anteriorly, are a little concave 
posteriorly. The length of the antepenultimate joint measures 
about two-thirds that of the penultimate, its posterior margin is 
a little concave, so that the lateral margins are somewhat shorter 
than the length of this joint in the middle line. The lateral 
margins of this and of the following fourth joint are straight, but 
those of the fifth are rounded; in P. consobrinuwm, however, this 
latter is also straight. As regards the coarse punctation, P. lati- 
dactylum agrees with P. consobrinum. 
In the two males from the River Prah the right chelipede is a 
little larger than the left; in the very young one from Liberia 
the left isa little larger. The upper margin of the arm of the 
larger male from the River Prah bears some transverse rugosities, 
and one observes a small tubercle on the concave upper surface at 
the proximal end, somewhat nearer to the upper than to the 
anterior margin; the latter is also somewhat tubercular on its 
proximal half. The anterior surface of the arm bears, near the 
articulation of the wrist, a conical tubercle not far from the 
anterior margin, and a lower, broader tubercle between it anc 
