BRUSH AND COMB 299 
Cumidz the inner branch has a little process on the outer 
margin carrying the supposed auditory hairs. 
The appendages of the sixth pleon-segment, the 
uropods, almost always have the peduncle elongate. The 
inner branch may consist of one, two, or three joints, while 
the outer appears to be always two-jointed. Living 
Cumacea will be seen repeatedly to double this caudal fork 
back upon the head, some species being in the habit of 
folding it dorsally and others ventrally. Hugéne Hesse 
remarks that he has frequently seen these animals pass the 
different appendages of the body and the mouth-organs 
successively between the uropods as if between the teeth 
of acomb. These appendages are often plentifully sup- 
plied with spines and hairs, so that they can well fulfil the 
functions both of brush and comb in the creature’s toilet. 
Like so many other marine animals, which live in con- 
ditions very unpromising for cleanliness, these can pro- 
bably keep themselves exquisitely neat when they so desire, 
although if they are killed with the mud and slime upon 
them, it is extremely difficult for human fingers to cleanse 
the specimens without inflicting damage. ‘The tail part in 
the Cumacea has the advantage of being very conspicuously 
displayed, and the combined characters of the telson and 
uropods, or, when there is no articulated telson, the 
characters of the uropods alone, will suffice to determine 
the genus to which a specimen belongs. 
The shape and armature of the carapace are of the 
highest importance for specific distinction, but the charac- 
ters are not always especially easy to observe, and the 
matter is complicated by the differences which prevail not 
only between the males and females, but between the forms 
of the male at different periods of life. Normally the 
antero-lateral angles of the carapace are produced so as to 
surround the front of the head, and by meeting above to 
form a sort of rostral process. The median fissure of this 
quasi-rostrum being continued backwards on either side 
gives a kind of trilobed appearance to the head. Occa- 
sionally, as in Vaunthompsonia cristata, Spence Bate, the 
ocular prominence of the head projects so far that the 
