288 DR. J. G. DE MAN ON THE PODOPHTHALMOUS 
differences. The rostrum is styliform in its distal half, very 
acute, and projects straightly forwards, being never curved 
upward towards its extremity ; it is continued backwards into a 
short ridge which does not attain the posterior margin of the 
carapace, and which in most specimens is slightly flattened or 
even slightly suleate for a part. The rostrum is dentate, 
the formula being in three specimens _ in two and in the two 
remaining i; the first tooth, 7. e. its point, is placed a little 
before the middle of the cephalothorax, aud constantly a little 
behind the hepatic spine, whereas in P. zndicus this spine is 
found precisely below, and not before, the point of the first tooth 
of the rostrum. The distance of the first tooth from the second 
is a little longer than the distance between the second and the 
third; the intervals between the other teeth of the upper 
margin slightly increase distally, the most anterior tooth being 
separated from the apex of the rostrum by an interval which 
is as long as, or even a little shorter than, that which separates 
it from the preceding. The teeth of the lower border are smaller 
than those of the upper; their intervals also increase slightly in 
length, and the foremost stands closer to the apex of the rostrum 
than the foremost tooth of the upper border. Whereas the 
distal half of the rostrum is styliform, the proximal half which is 
found on the carapace is more or less elevated into a high crest, 
characteristic of our species. 
The antennal and the hepatic spines are both very small, 
much smaller than those of P. semisulcatus; other spines are 
not found on the carapace. The antennal and the hepatic sulci 
are very deep in P. semisulcatus, whereas in this species they are 
faintly defined, especially the latter. The gastro-hepatic sulcus 
is also faintly defined, just as in P. semisulcatus. 
The first, second, and third segments of the postabdomen are 
rounded on their dorsal surfaces; the fourth is keeled, but the keel 
occurs only on the posterior two thirds of the dorsal line; the 
fifth and the sixth segments are also carinate, the acute keel of 
the sixth terminating posteriorly in a short acute tooth. The 
terminal segment is unarmed and provided with a rather deep 
longitudinal groove on the middle of its dorsal surface. The 
first, second, fourth, and fifth segments are marked with a small 
notch on each side posteriorly. The “ventral plate” of the 
female much resembles that of P. indicus, M.-Edw. (Spence 
Bate, l. c. pl. xii. fig. 5), but is somewhat less distinctly circular ; 
