GAMMARlDvE. 
tail are armed with a central dorsal tooth, directed pos- 
teriorly. The eyes are kidney-shaped. The antennas 
are short, being scarcely one-sixth the length of the 
animal. The first pair of legs are slender and weak, 
with the finger obsolete. The second pair of legs are 
scarcely stouter than the first, and terminate in an im- 
perfectly chelate organ. The walking legs are tolerably 
robust, and differ from those of I. ohesa only in having 
the thighs of the last three pairs produced posteriorly 
in two sharp points or teeth. The last three pairs of 
caudal appendages are nearly of the same length, and 
the central tail-piece is emarginate at the apex. 
Several specimens of this species were taken by Pro- 
fessor Kinahan, from the branchial cavities of Rhizostoma 
Cuvieri. The specimen from which our figure and de- 
scription were taken is preserved, in an imperfect state, 
in the Dublin Museum. M. Guerin-Meneville had some 
specimens in his collection, procured on the western 
coast of England. 
The circumstance of this animal having been found 
inhabiting the gill-cavities of a Medusa establishes 
another link associating this subfamily more closely 
with the Hyperina than was at first presumed. 
