E nc avid a — Decapo da . 
51 
Sub-order I. — MACRURA. 
The Macrura are generally distinguished by the large size of Table- 
the abdomen, which is symmetrical and not folded under the body. Nos -^g 
The front, or rostrum, is not united with the “ epistome.” The 
sixth pair of abdominal appendages (uropods) are always 
present, generally broad and flattened, forming with the telson, 
a “ Tail-fan.” 
The first Tribe of the Macrura, the Penaeidea, consists of Table-case 
prawn-like animals having the first three pairs of legs usually No ‘ 9l 
chelate or pincer-like, and not differing greatly in size. The side- 
plates of the second abdominal somite do not overlap those of the 
first. Members of this Tribe are the commonest Prawns in tropical 
seas, and often reach a great size. Penaeus caramote (Fig. 31) is 
highly esteemed for the table in Mediterranean countries, and 
many other species are used for food in various parts of the 
world. P. caramote is stated to have occurred on the Welsh 
coast. Leucifer, a delicate, transparent, pelagic form, belong- 
ing to this tribe, differs from all other Decapoda in having no 
gills. 
The small Tribe of the Stenopidea includes a few forms which 
resemble the Penaeidea and the Astacidea in having the first three 
pairs of legs chelate, but differ from them, among other characters, 
in the fact that the third pair is much the largest. Stenopus, a 
common tropical genus, is remarkable for the brilliant colora- 
tion of the living animals. The specimen of S. hispidus ex- 
hibited here has been painted so as to convey some impression 
of this. 
The Tribe Caridea includes the true Prawns and Shrimps. 
The first two pairs of legs are generally chelate-or pincer-like, and 
the first is seldom larger than the second. The second somite of 
the abdomen has the side-plates broadened, so as to overlap those 
of the somites in front and behind. 
Only a few of the numerous families composing this tribe are 
illustrated by the specimens exhibited. 
The members of the family Acanthephyridae are deep-sea 
animals, and possess many primitive characters. Like some of 
the related families, they have swimming branches (exopodites) on 
the legs. Some of them are phosphorescent. 
The Nematocarcinidae are also inhabitants of the deep sea, and 
are remarkable for the extreme length and slenderness of the legs, 
