ISOPODA. 7 



The second antenna in the female has five joints : the first is short, the next two 

 are a little longer and subequal, the fourth is very nearly as long as these three 

 together, the terminal one is about as long as the second or third, but of course a great 

 deal more slender. This one terminates in a group 'of six long setae ; setae occur 

 distally on all the joints except the first. 



In the female the mandible is strong, the cutting edge is incurved almost to a 

 right angle and armed with three large teeth, a broad one behind the other two. The 

 molar tubercle is long, at right angles to the main structure ; it is slightly swollen and 

 then tapers to its posterior border. This edge bears five well-developed teeth and a 

 discoloured tubercle within this on the posterior border. The mandible of the opposite 

 side has a well-developed cutting edge with a prominent tubercle posteriorly, but there 

 are no long teeth here. There is no palp. 



The first maxilla has a broad base, the external margin rapidly tapering to a 

 slender band-like structure. It is much curved inwards distally, and armed with some 

 half-dozen strong teeth, one of which, the most external, is longer than the rest. The 

 so-called palp rises from the inner margin of the base, and is a slender structure about 

 two-thirds the length of the main lobe, and terminating in two long setae. 



The second maxilla is only represented by a small ovoid lobe. 



The maxillipeds together have a median, heart-shaped basal joint, which is 

 divided longitudinally ; the masticatory lobe is more than half the length of the 

 basal joint, slightly increasing in diameter to the end, which is truncate, armed with a 

 couple of small tubercles and quite devoid of any setae. 



The palp is five-jointed. The first joint is very small, the second is the longest 

 with an oblique distal margin, the third is triangular in shape, the apex external, and 

 therefore this side of the joint is reduced to a minimum ; the fourth joint is large, and the 

 terminal about half the length and much more slender ; this is armed with four long setae. 



The epignath is about three-quarters the length of the basal joint and irregularly 

 ovoid. 



The first appendage of the mesosome, or chelipeds, of the adult male are very 

 largely developed. The ischium is a broad joint prolonged below the point of its 

 articulation to a broad, curved edge, like an axe-blade. The merus is a very short 

 joint, wedged in obliquely between the ischium and the carpus. The carpus, excepting 

 the dactylus, is the longest joint of the limb ; it is very broad and rounded 

 posteriorly. Its inner margin is produced into a knife edge. The propodus is a 

 stout joint about half the length of the dactylus, and carries, on its inner side, 

 at right angles to it, a large irregularly-shaped appendage which forms a chela with 

 the dactylus. This appendage is curved ; the proximal portion is broad, flattened, 

 and produced into a stout spur, directed inwards. The distal portion is more slender, 

 having a swelling with a few (three) long setae on its inner side, beyond which it 

 terminates in a slender incurved finger. The dactylus is very long, slender, and 

 curved, longer than any other joint in the appendage. 



