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 relatcil 

 to Leptantliura. 



Leptanthura glacialis. 



(Plate I., fig. 1.) 

 Specific characters : — 



Uropofla as lonjj as the metasonie, broad ; the exopodite rather le^« than half the lenf^th of the 

 endopodite and cordate in shape. 



This species attains a length of 21 mm. 



The cephalosome is the smallest segment of tlie body, and its anterior margin is 

 incurved to be produced in the middle line into a short point between the insertion of 

 the antennae. There are no eyes. 



The mesosome comprises seven distinct segments, the.sc 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 subequul, 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 setae. 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 setae. 



The second antenna (fig. lb) comprises a peduncle of f<jur very short joints ; of 

 the first the iimer margin is much swollen, the next joint is attached at an angle and 

 has a rounded ba.se, 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 setae. 'J'he 

 flagellum comprises five joints, the first is the largest, the other four are very small, all 

 are fringed distally with long .setae, 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. Ic) is a single comparatively broa<l joint tapering to a fine point. 



The maxillipcd (fig. Id) is elongated and has its inner edge straight, the outer one 

 being rather rounded to the extremity. The masticatory lo])e, such as it is, is 

 represented only by a minute conical joint bearing a single seta, a small palp of a 



VOL. V. I 



