1G4 



The remaining portion of the second pleopod is branchial in 

 function. The rest of the endopodite is similar to that of the first 

 pleopod, margins free from setre and with an emargination at the 

 distal end. Tlie exopodite consists of two joints, the first one sub- 

 elliptical with a rounded lobe extending back along the outer 

 margin of the base and partially covering it, both margins are 

 fringed with set;w, those near the proximal end simple, but those 

 at the distal end very long and densely plumose ; the second joint 

 is small, elliptical, and has the margin fringed with twelve very 

 long plumose setie. 



The second pleopoda in the female differ from those of the male 

 only in the absence of the "penial filament," as the result of 

 which the base of the endopodite is not swollen and does not con- 

 tain the powerful muscles found in the male. 



The third pleopoda (Plate xxvi., fig. 3) are similar to the second 

 pleopoda (of the female) except that the exopodite has the first 

 joint more narrowed distally. Ai'ising from the outer margin of 

 the basal portion (the protopodite) is an ovate appendage which 

 perhaps represents the epipodite. The margins are fringed with 

 long simple sette and the integument appears thin and delicate so 

 that this portion probably is branchial like the rest of the pleopod. 

 I have not found this appendage in the first and second j^airs of 

 pleopoda. 



The fourfh nudft/fh pleopoda (Plate xxvi., fig. 4) are similar in 

 all respects to the third, but the endopodite gradually increases in 

 size as compared with the exopodite, till in the fifth pleopod it 

 reaches to the end or somewhat beyond the end of the first joint 

 of the exopodite.* 



* Attached to the pleopoda and apparently partially imbedded in the 

 integument, I have frequently found a number of oval or eg^g-shaped 

 bodies, the real nature of which I have not been able to ascertain. They 

 may perhaps be alg-a; of some kind. Beddard found a "number of green 

 bodies of varying form " in the interior of the thoracic appendages of 

 Astrurus crucicauda, which he took to be parasitic algaj. He also refers 

 to the fact that parasitic Infusorians ( Anoj^lojihyra circulayis, Balbrani, 

 Eecueil Zool. Suisse, ii., 1885, p. 277) are known from the appendages of 

 Asellus. [See 'Report of the "Challenger" Isopoda,' Part II., p. 38, 

 footnote ] In one of the specimens of Phreatoicus australis I found in 

 some of the thoracic legs a number of oval bodies, which I at first thought 

 were the same as those found on the pleopoda, but they diifor in some 

 points and are perhaps different — possibly they are infusorians of some 

 kind. They are not quite 1/50 inch in length, elliptical, about half as 

 broad as long, surface smooth, and they have been deeply stained by the 

 borax-carmine with which I stained the appendages before mounting 

 them, the thick outer portion or integument has not been stained so 

 deejily as the inside. The bodies found on the pleopoda appear to bo on 

 the surface and partially imbedded in the integument ; they ai-e of about 

 the same size but have scarcely been stained by the borax-carmine and 

 ajipear yellowish and have the surface much wrinkled ; some of them are 

 shown in position in Plate xxvi., fig. 4 at a, and an enlarged view of one 



