‘\ me 
(9 CRAM Aare L ; Werwnours ) 
ANTHURA GRACILIS. 161 
THIs species{is well defined by the strong, raised, 
lateral margins to the segments of the body and tail, 
by the consolidation of the basal segments of the latter 
almost into a solid mass, the articulations being, how- 
ever, clearly indicated by impressions on the under edge 
of the lateral margin, and especially by the characters 
of the terminal segment of the tail and its appendages, 
noticed in the specific characters given above. It is, 
however, rather difficult to describe precisely the curious 
construction of this terminal portion of the body. 
Montagu says that “the body is terminated by 
five large caudal appendages truncated at their ends, 
these are deflected nearly at right-angles with the body, 
the middle one fixed, and the lateral ones jointed and 
spread a little upwards in a semicircular form.” ‘The last 
term is not, however, at all expressive, and should, 
doubtless, have been “ semicylindrical,” since the ap- 
paratus, when open, forms a concave cup-like disc, and 
when at rest, from being affixed vertically, the outer 
plate falls back and shuts down upon the dorsum of the 
middle tail-plate, like the two wings of a closed triptych. 
The irregularly crenulated margin of the extremity of 
these caudal plates also affords another distinctive cha- 
racter. Not having seen fresh specimens of this species, 
we are unable to give a more precise description of the 
antennze than is conveyed in our generic observations. 
The fore legs, although not longer than the succeeding 
pairs, are very much more robust, with a large, elongate- 
ovate hand, the upper basal angle being swollen, and the 
palm having a deep incision along its outer half (which 
we believe to be caused by the elongation of the outer 
and lower angle of the preceding joint) which is slightly 
rugose. The other legs are much more slender, with the 
joints of nearly equal length, the fifth and sixth having 
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