1366 THE VOYAGE OF H.M.S. CHALLENGER. 



Remarks. — In one of the female specimens the third perseopods approach those of the 

 male in the comparative shortness of the fourth joint, which has only seven teeth on the 

 combined front and palmar margin ; in this specimen one of the branchial vesicles of the 

 fourth peraeopods was normal, the other dwindled ; small marsupial plates were developed 

 to the first, second, and third perseopods, not overlapping as in the adult female but 

 hanging down like small branchial vesicles ; those of the second perseopods were the 

 largest, these and the following pair being attached to the ventral surface of the animal 

 a little in front of the branchial vesicles. Considerable as are the differences between the 

 male and the females, there can be little or no doubt that these specimens all belong to 

 the same species ; they were taken together ; they all have the same yellowish tone of 

 colouring in spirits, and the intermediate character of the young females corroborates 

 what is on other grounds probable. 



It is possible that some of the specimens here described ought to be assigned to new 

 species, but it seems so extremely uncertain whether the differences observed do not 

 belong merely to age, sex, or individual peculiarity, that the distinguishing names 

 originally chosen have been relinquished. Streets, in changing the name of his 

 own Anchylonyx hamatus into Phronimella elongata, Claus, says that the second 

 uropods are well developed in the male, and figures them with two rami. In no 

 specimen, either from the Atlantic or the Pacific, have I been able to find biramous 

 second uropods, and am therefore unable to say whether the solitary specimen of a male 

 examined by Streets constitutes a separate species, Phronimella hamata, or is only one 

 stage of development in the life-history of a species common to the whole circumference 

 of the globe. 



Phronimella elongata. Specimens C, D. 



Male. — The seventh segment of the peraeon and first three segments of the pleon 

 deeper and less elongate than in the female, the fourth segment of the pleon also 

 shorter ; the first three segments of the pleon with the postero-lateral angles produced 

 into a tooth, the hind margin a little higher up projecting not into a tooth but a 

 rounded angle. 



U])per Antennee- — The peduncle short, with only two joints, the second shorter than 

 the first ; the flagellum eleven-jointed, the first joint large and of great length, the breast 

 unarmed, apically a little produced but not reaching to the end of the joint, which is 

 distally narrowed and carries a row of seven filaments commencing near but not on the 

 distal part of the breast ; the remaining ten joints are together shorter than the first and 

 successively narrower, all longer than broad, but by no means linear, the last conical 

 with a little setule at the tip. 



Lower Antennse. — The boss containing the antennary gland has an obtuse-angled 



