98 Memoirs of the Indian Museum. [Vou. IV, 
The carapace is smooth, without carinae, and is considerably longer than its great- 
est breadth. The gastric grooves converge anteriorly ; of the cervical groove no trace 
remains. ‘The antero-lateral angles are rounded. ‘The rostrum is fully one and a half 
times as broad as long, widest in front of the base, and its strongly rounded, lateral 
margins meet apically in a very broad, obtuse, and almost obsolete angle. 
The eyes are cylindrical and about as long as the greatest breadth of the rostrum. 
The cornea scarcely exceeds the breadth of the stalk and is set very obliquely on it. 
It is traversed laterally, both inside and outside, by a narrow longitudinal band com- 
posed of fine parallel grooves. The antennular peduncle is about half the length of 
the carapace and rostrum combined. The dorsal process of the proximal segment of 
the antennal protopodite is flat above and the margin of the vertical keel on its ventral 
surface is concave in lateral view. 
The carpus of the raptorial claw is bluntly carinate dorsally ; the propodus bears 
three movable spines at the base of its pectinate margin and the dactylusis very slender, 
convex externally, and possesses three long flattened teeth including the apical 
one. 
The exposed thoracic somites are smooth dorsally. The fifth has a deep vertical 
groove on its lateral face. The lateral margins of the sixth somite are truncate ; those 
of the seventh are less sharply truncate and, owing to the oblique antero- and postero- 
lateral edges, are much narrower. ‘The eighth somite is narrowly rounded laterally 
with a small and deeply incised apical notch. 
The first five abdominal somites are smooth except for a deep Y-shaped groove on 
the lateral face of the first and for a pair of conspicuous pits on each of the four succeed- 
ing somites. The postero-lateral angles of the fourth end in a small spine in Atlantic 
specimens and in some from the Indo-pacific; those of the fifth somite are invariably 
spinous. The sixth somite has a pair of strong submedian spines on its posterior 
margin and a similar pair at the postero-lateral angles. Between these two pairs 
there is an additional spine on either side which springs from the middle of the somite 
and does not quite reach to the distal edge. The abdomen is very strongly arched 
from side to side and its greatest breadth is contained rather less than five and a half 
times in the total length. 
The telson bears seven carinae on its dorsal surface, the first and second laterals 
being absent. The median carina is high and sharp and terminates in a strong spine 
which may reach as far as the distal margin. ‘The submedians are low and in young 
examples inconspicuous ; they converge distally to the posterior end of the median 
carina and are absent in the anterior third of the telson. ‘The intermediate carinae 
are strong, posteriorly divergent, and end abruptly in a sub-acute apex. The marginal 
carinae are externally curved and reach the edge of the telson in front of the posterior 
marginal tooth. Inside this carina near the proximal end there is a small tubercle. 
On the margin there are six large spines : a pair of long movable submedians and two 
pairs, the intermediates and laterals, which are fixed. The edge between the sub- 
medians is usually rather deeply incised, rarely entire. On the inner side of the inter- 
mediates there is a minute spinule succeeded by a rounded lobe and the margin 
