ISOPODA. 9 
essential features upon which this separation is based, but under any circumstances 
the two genera are very closely allied. The following species is most nearly related 
to Leptanthura. 
LEPTANTHURA GLACIALIS. 
(Plate I, fig. 1.) 
Specific characters :— 
Uropoda as long as the metasome, broad ; ‘the exopodite rather less than half the length of the 
endopodite and cordate in shape. 
This species attains a length of 21 mm. 
The cephalosome is the smallest segment of the body, and its anterior margin is 
incurved to be produced in the middle line into a short point between the insertion of 
the antennee. There are no eyes. 
The mesosome comprises seven distinct segments, these are elongated, and the first 
is longer than the cephalon, the two following are very little longer and subequal, the 
two succeeding ones are a little longer still and subequal, the last is very little shorter 
than the first. 
The metasome is narrower and all the segments are distinct. The first and fifth 
are rather the longest, the intermediate ones being subequal in size, the sixth is 
narrower and longer, having the posterior margin rounded. 
The telson is elongate, linguiform tapering to a blunt point, which is setose. The 
uropods are large and with the telson form a conspicuous caudal fan. 
The first antenna (fig. la) has a peduncle of three stout joints, progressively 
shortening from the first, the third only having a distal fringe of long sete. The 
flagellum consists of four joints, the first being broad but extremely short, so much so 
as to be easily overlooked ; the next joint is comparatively long, the two terminals 
progressively shorten but are together half the size of the preceding one ; both, more 
particularly the terminal one, are provided with long sete. 
The second antenna (fig. 1b) comprises a peduncle of four very short joints ; of 
the first the inner margin is much swollen, the next joint is attached at an angle and 
has a rounded base, otherwise it is very short and stout; the two following are 
subequal in length, but the more distal one, though still stout, is little more than half 
the diameter of the proximal one; both are fringed distally with long set. The 
flagellum comprises five joints, the first is the largest, the other four are very small, all 
are fringed distally with long sete, those of the terminal joint forming a dense tuft 
quite concealing all details as to the character of this joint. 
The mandible is triangular, pointed, and bears a diminutive palp, in which I have 
only been able to discern two joints. 
The maxilla (fig. 1c) is a single comparatively broad joint tapering to a fine point. 
The maxilliped (fig. 1d) is elongated and has its inner edge straight, the outer one 
being rather rounded to the extremity. The masticatory lobe, such as it is, is 
represented only by a minute conical joint bearing a single seta, a small palp of a 
VOL. V. I 
