480 PROFESSOR CHARLES CHILTON ON THE 
of Metopa sarsu Pfeffer. ‘This specimen I have been allowed to dissect and mount 
permanently as a micro-slide, and I find it agrees precisely with MZ. walkeri Chevreux, 
a name which must therefore be dropped in favour of the older M. sarsv. 
My specimens agree minutely with CHrvREUx’s description; the accessory 
flagellum is, I think, present in all the specimens, but it is exceedingly small, so small 
that it would hardly be inaccurate to say that it is absent. CHEvrevx describes the 
palp of the mandible as two-jointed ; I think there is a minute third joint present in 
the specimen from which I dissected the mouth parts, but if so it is almost as small as 
the accessory flagellum ; yet the presence or absence of these minute joints is one of 
the distinguishing marks for some of the genera into which the family Metopide is 
now divided. 
CHEVREUX was unable to identify his species with any of those described by 
STEBBING in the Challenger Report, but says it seems to be nearest to Metopa ovata ; but 
this species has the basal joints of pereeopods four and five narrow, and is now placed 
in the genus Metopella. I would rather be inclined to compare it to M. magellanica 
or M. compacta, species now placed in the genus Metopoides, while the small acute 
teeth which are present on the palm of the second gnathopod, as described by 
CHEVREUX, show an approach to the more irregular palm found in M. crenatipalma, a 
species now known as Proboloides crenatipalma. 
From the Challenger collections Srrspine described six species of Metopa—one 
from Kerguelen Island, the other five from Cape Virgins, off Patagonia; each of which, 
with one exception, was represented by one specimen only, though of one species 
another specimen was found at Nightingale Island in the Tristan da Cunha group. Of 
these six species three are placed in Das Tierreich Amphipoda under Metopoides, two 
under Metopella, and the other under Proboloides. As these genera are separated 
from one another and from Metopa by small points such as those I have mentioned 
above, and as there are altogether twenty-one species of Metopa, six of Metopella, 
three of Metopordes, and seven of Proboloides, it is not to be wondered at that the 
classification of the family is admittedly in an unsatisfactory condition, and I think it 
wisest not to attempt to identify the species under consideration with any of the 
Challenger species, although it is probably the same as one of the species described 
from Cape Virgins. 
The sides of the last seement of the urus are raised into a vertical plate on each 
side of the telson, and this is continued by a similar vertical plate on the outer edge 
of the peduncle of the third uropod, so that a groove is formed, protected on each side 
by these vertical plates or flanges, in which the telson may rest when the animal swims 
by backward strokes of the hinder part of the body (see Piate I. fig. 10). 
