BRUSH AND COMB 299 



Cumidsethe 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 if dorsally and others ventrally. EugSne 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 a comb. 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 



