67 



this position the antennules are protected by the massive basal 

 joint below, and by the rostrum above. On the same joint there 

 is the slit-like opening of the auditory sac. From the exterior 

 margin of the latter there grow inwards a row of long hairs, 

 which form a protective covering to the opening. The slit widens 

 towards the proximal end, and is here partly covered by a rounded 

 flap. The second and third peduncular joints are about equal 

 in length. 



The outer flagellum is very thick at the base, but tapers 

 rapidly ; it is composed of fifteen joints, and has a dense fringe 

 of setae on its inner margin. The inner flagellum is composed 

 of only six joints and is uniformly slender throughout. 



The first, and largest, joint of the antennal peduncle has a 

 sharp spine at the antero-interior angle ; there is no trace of 

 a scale. The flagellum is as long as the chelipeds in the female, 

 but scarcely reaches to the middle of the propodite in the male. 

 The first two joints of the third maxillipedes are short and 

 broad. A small epipodite is attached to the coxa. The exopodite 

 has a long peduncle which extends beyond the merus ; it narrows 

 suddenly in its distal third ; the flagellum has one long basal 

 joint, the rest being made up of short joints, each of which 

 bears two long setae. The ischium is shorter than the merus, 

 its lower distal extremity ends in three teeth. The linea cristata 

 bears about twenty-two teeth. On the inner side of the merus 

 there are two large spines ; one is situated at the distal end, 

 and the other near the middle, but rather nearer the distal 

 than the proximal extremity. Both ischium and merus bear 

 fringes of long setae. The carpus is slightly swollen in its second 

 half, and is of about the same length as the propodite. The 

 dactyl is shorter than both. 



In the young male the chelipeds are similar to those of the 

 female ; in the adult, however, they become developed to a 

 relatively enormous size, being about twice the length of the 

 body (with the abdomen in its natural folded position). The 

 elongation is accompanied by great thickening, and the unwieldy 

 appearance of the appendage is enhanced by the fact that the 

 first three joints remain slender. The thickening begins at the 

 proximal end of the merus. The largest joint is the propodite. 

 The two chelipeds are unequal, sometimes the right, sometimes 

 the left, being the larger. In the latter the distal part of the 

 propodite is peculiarly modified ; the fixed finger curves strongly 

 outwards from, the point of articulation of the dactyl, and meets 

 the latter only at its tip. Opposite the curve there is a strong 

 tubercle on the inner margin of the dactyl. The surface of the 

 chelipeds is covered with scale-like tubercles, especially in adult 

 males. The curve in the fixed finger does not seem to develop 

 until the animal has attained maturity. Of two large males 

 in the collection at my disposal, one has the curve and opposite 

 tubercle very prominently developed, whereas in the other, 

 which is only very slightly smaller, there is no trace of it, and 

 the fingers are in contact throughout their entire length. 



