CRUSTACEA OF THE MERGUI ARCHIPELAGO. 297 
raptorial limbs being armed with three spines besides the elon- 
gated curved terminal spine, and by the armature of the distal 
prolongation of the base of the uropoda. But Pseudosquilla 
ptlaensis is so much the more interesting, because it forms a 
transition from the genus Pseudosquilla to the genus Lysiosquilla, 
(1) by the eye-peduncles being dilated at the distal end, having 
the cornea bilobate, (2) by the terminal segment of the post- 
abdomen being transverse, much broader than long. 
In its outer appearance this species agrees more or less with 
the Japanese Lysiosquilla latifrons (Fauna Japonica, pl. li. fig. 3). 
The carapace is but little longer than broad, is little narrowed 
anteriorly, its antero-lateral angles are rather obtuse, and its 
postero-lateral ones are broadly rounded. .The upper surface 
is smooth, even when seen under a magnifying-glass, and 
presents the two ordinary, longitudinal, submedian sutures, which 
are straight and continuous, from the anterior to the posterior 
margin, but no transverse cervical suture. As in Pseudo- 
squilla Cerisii, the rostral plate terminates in a prominent, acute 
spine, which projects a little beyond the eyes, though not reaching 
_ the distal end of the antepenultimate joint of the internal antenne ; 
the basal portion of the plate is more than twice as broad as long, 
and its antero-lateral angles are rather obtuse. The upper 
surface of the rostral plate is perfectly smooth. The eye- 
peduncles are short, reaching only to the middle of the ante- 
penultimate joint of the internal antenne ; they are dilated at 
their distal ends, and the cornea is bilobate, presenting a larger 
internal and a somewhat smaller external lobe. The internal 
antenne have the ordinary length, ther peduncles being as long 
as the carapace ; the last joint cf the peduncle is a little shorter 
than the penultimate, whereas in most species of the genus 
Pseudosquilla it is longer. The flagella of the internal antenne 
are a little shorter then their peduncles, and the latter does not 
extend as far forward as the external antenne, which are a little 
longer. 
The upper surfaces of the four exposed thoracic segments and 
of the segments of the postabdomen are rounded and smooth ; 
the first exposed thoracic segment is laterally prolonged into a 
very short acute lobe, constituting the lateral angles of the 
posterior margin. The two following are laterally rounded, with 
entire margins, whereas the last presents a very small subacute 
prominence, The fifth or antepenultimate segment of the post- 
