304 THE VOYAGE OF H.M.S. CHALLENGER. 



Habitat.— Station 200, October 23, 1874 ; lat. 6° 47' N., long. 122° 28' E.; near the 

 Philippine Islands ; depth, 250 fathoms ; bottom, green mud. Two male specimens, one 

 having the petasma more developed than the other. Trawled. 



The general surface of the animal is slightly pilose. The rostrum is horizontal, pointed, 

 is not elevated at the apex, and does not reach beyond the distal extremity of the first 

 joint of the peduncle of the first pair of antennae ; the upper margin is armed with 

 three teeth, of which the anterior is near the apex and the posterior behind the 

 orbital margin, and they stand upon a small compressed carina which fades away upon 

 the gastric region, and does not reappear until at the fourth somite of the pleon, where 

 it is slightly elevated, and it terminates in a small tooth at the posterior extremity of 

 each of the last three somites. 



The ophthalmi are large, orbicular, and supported on short, narrow and compressed 

 peduncles that have a small tubercle on the inner side close to the eye. 



The first pair of antennae has the peduncle twice as long as the rostrum, and the first 

 joint has a stylocerite that lies in contact with the margin, and terminates in a tooth a 

 little short of the outer distal angle, which is also produced to a sharp tooth ; the second 

 joint is nearly as long as the first, and the third carries on the outer side a short, flattened 

 flagellum, and at the extremity one that is once and a half as long as the animal, and 

 which has near the base a slight but unusual curve and twist, corresponding to the length 

 of the outer flagellum, and apparently due to its oblique compression. 



The second pair has the phymacerite projecting downwards and inwards, and the 

 scaphocerite extending forwards beyond the distal extremity of the smaller flagellum, 

 and in both specimens in the Challenger collection the margins are thickened. In one 

 specimen this thickened tissue is limited to the outer distal margin, commencing just 

 beyond the small tooth and fading away at the apex, but the structure beyond exhibits 

 evidence of being affected. In the other specimen the same dense substance commences 

 at the corresponding point, that is, at the fissui*e beyond the outer tooth, and continues 

 to about halfway on the internal margin, where it gradually decreases and terminates. 

 I believe this thickening to be the result of disease, but it appears to produce in some 

 specimens a singular constriction of the organ that is worthy of consideration as pro- 

 ducing alteration of form, which appears to resemble specific variation {vide PI. L. a). 



The mandible carries a synaphipod of which the terminal joint is triangulate. 



The first pair of gnathopoda carries a basecphysis that extends considerably beyond 

 the dactylos. The second reaches as far as the extremity of the rostrum and supports a 

 basecphysis that reaches to the extremity of the meros. 



The pereiopoda approximate to each other ventrally, the coxa? of first three pairs being 

 almost in contact. Between the fourth pair is a small, pointed, obliquely projecting plate. 

 The coxae of the posterior pair are developed to an unusually large size, and approximate to 



