Al6 APPENDIX. No. IV. 
April and twentieth of May, and were not seen afterwards, although 
the preceeding sort were still abundant. 
Gen. II. Atima. Thorax elongate with the sides not approximating. Mouth 
placed towards the hinder part of the thorax. 
Sp. 1. Alima hyalina. Occurred abandeney at Porto Praya, and in 7, 37, 0 N. 
lat. 17, 34, 15 Wi. long. 
Puytiosoma,* the most curious genus of crustacea that has yet been dis- 
covered, and of which there are at least four very distinct species, occurred 
in the greatest profusion from the 10th April to the 30th May. The shell 
of this genus is membranaceous and as thin as a leaf; the part containing 
the mouth, and from whence the legs arise, is drawn backwards and pro- 
jects beyond the hinder part of the shell. The front of the shell bears the 
eyes and antennz: the eyes have the first joint of their peduncles very much 
elongated ; the second joint is short, and the eyes themselves are abruptly 
larger than their peduncles. The superior antenne are (as in all the other 
malacostraca with pedunculated eyes) bifid. The inferior antenna are vari- 
able in their projection, and form, affording characters which, for the present, 
I shall only venture to use for the purpose of specific distinctions. The 
abdomen has the usual appendages beneath, and those of the last joint are 
converted into swimming or rather steering lamella. ‘The mouth, when first 
viewed, appears to be trilobate; this arises from a clypeus similar to that 
covering the mouth of Squwilla, and the prominence of the exterior sides of 
the mandibles, which are much curved and dilated towards their middle ; 
their points are bifid, and one lacinia is unidentate within. Two pairs of 
maxilla are very distinctly to be seen; the outer ones are terminated by 
three spines. I have not had time to ascertain the modification of the 
interior ones, nor to ascertain the existence and insertion of the palpi. The 
front pair of legs is extremely short and dilated at its base, with all the 
joints (the first excepted ?) confluent. The second pair is short; the third 
joint at its base has a flagrum which is articulated towards its point; the 
last jomt is terminated by long spines and a claw with unequal spmes. The 
five following pairs of legs are very long, and the hinder ones gradually 
* The third, fourth, fifth, sixth, and seventh pairs of legs, in the numerous speci- 
mens sent home, were for the most part broken off at their third joint, the flagrum only 
remaining. See the plate. 
