294 DE. J. G. DE MAN ON THE PODOPHTHALMOUS 



this singular tooth. The slender carpopodites reach to the 

 anterior margin o£ the cephalothorax, and are a little shorter 

 than the meropodites. The propodites are quite half as long as 

 the meropodites, and the straight, acute dactylopodites are still 

 a little shorter than the propodites. 



As regards the female of this species, there is the strange fact 

 that two of the eight female specimens differ slightly from the 

 others by the structure of the last pair of legs and of the 

 " ventral plate." These two specimens, however, completely 

 agree in all other characters with the remaining six individuals. 



The fourth pair of legs of the female are as long as in the 

 male, reaching as far forwards as the anterior legs ; these legs 

 also fully resemble the corresponding legs o£ the male, but their 

 meropodites are simple and not enlarged. The fifth pair of 

 legs of both females are about as long as those of the male and 

 are similar to them, but the meropodites are simple and do not 

 present the peculiar notch and the characteristic surmounting 

 tooth of the male. In six female specimens, which I shall speak 

 of as A, the upper margin of the ischium-joint of the fifth pair 

 of legs is dilated into a small, compressed, lamellate, triangular 

 ■ crest, broadest posteriorly and gradually tapering towards the 

 distal end of the joint. In the two other female specimens 

 (B) this crest is wanting, so that the ischiopodite presents the 

 same form as in the male. 



The singular organ called by Spence Bate the petasma 

 presents a very characteristic form in P. Lysianassa, but so 

 difficult to describe that I refer to the figure. The petasma, 

 which reaches anteriorly to the bases of the second legs, 

 consists of a longitudinal tube which presents a median longi- 

 tudinal fissure on the posterior surface ; the latter is convex 

 anteriorly and slightly concave posteriorly. Each lateral mar- 

 gin of the petasma presents a small triangular prominence about 

 its middle and directed forwards. At its distal end the petasma 

 is armed on each side with two spines or teeth, the proximal 

 ot which is very acute, and the anterior surface bears two pairs 

 of dentiform prominences, one pair near the base, the other near 

 the distal extremity. 



The rami of the uropoda are narrow, ovate, and much longer than 

 the terminal postabdominal segment ; they are slightly pubescent 

 above, and fringed as usual with hairs along the lateral margins. 

 In the male the outer surface of the basal joint of the uropoda 



