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 

 togetlier, 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 hmg 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 throe large teeth, a l)road one behind tlie otlier two. The 

 molar tubercle is long, at right angles to tlie 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 witli a prominent tubercle posteriorly, l)ut tliere 

 are no long teeth here. There is no palp. 



The first maxilla has a broad base, the external margin rapidly tiipcring 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. Tlie 

 so-called palp rises from the inner mai'gin 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 togetlier have a median, heart-shaped ba.sal 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 oblic^ue 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 ba.sal joint and irregularly 

 ovoid. 



The first appendage of the mesosome, or chclipeds, 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 dactylu.s. This appendage is curved ; the proximal portion is broad, flatteued, 

 and produced into a stout spur, directed inward.s. 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. 



