164 
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 setae and with an emargination at the 
distal end. The 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 setae, 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 setae. 
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. Arising 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 seta3 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 pairs of 
pleopoda. 
The fourth and fifth 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 egg-shaped 
bodies, the real nature of which I have not been able to ascertain. They 
may perhaps be algae 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 algse. He also refers 
to the fact that parasitic Infusorians (Anoplophyra circulans, Balbrani, 
Recueil 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 differ 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 
deeply as the inside. The bodies found on the pleopoda appear to be on 
the surface and partially imbedded in the integument ; they are of about 
the same size but have scarcely been stained by the borax-carmine and 
appear 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 
