KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 39. N:o ll. 71 
The following supplementary lines are given in order to complete former state- 
ments. 
In order to gain an exact idea of the true shape of a Phascolosoma, it is ne- 
cessary to examine fully extended animais. But not seldom it is a matter of great 
difficulty to preserve them in such a state. Singularly enough, different Phascolosoma- 
species do not react in the same manner when treated with one and the same fluid. 
Each species seems to require its specific treatment. With regard to Phascolosoma 
procerum, it always stretches to its whole extent when placed in a mixture of sea- 
water and very diluted alcohol (7 ”/5) in equal parts. However, it ought to be re- 
membered, that the animal must be in its full vigour, if a success is to be made. 
The body is elongate and slender, with the posterior extremity pointed (Figs. 
19, 20). The largest specimen examined -by me, had a total length of 50 Mm.; the 
distance between the posterior extremity of the trunk and the anal aperture amoun- 
ted to 10 mm.; the rest fell to the share of the proboscis including the foremost por- 
tion of the trunk. The two free segmental organs open exteriorly sligtly in front of 
the anal aperture (Fig. 26 s). The tentacles, arranged in six groups, vary in number 
(Figs. 21, 22 and 190). In six perfectly extended specimens I counted 28, 31, 36, 
37, 38 and 40. They are gutter-shaped, triangular in section (Fig. 28 t) and have 
the concave surface fairly densely ciliated. 
Immediately behind the tentacular crown the skin presents a narrow smooth 
girdle, limited posteriorly by a kind of collar or "fold" (Figs. 21, 22 and 28 f), 
which marks the anterior confine of the chitinous cuticle, which covers the main 
part of the body. A reference to the Synopsis of the genus will make it evident 
that hooks are absent. 
The colour is whitish gray, except on the "foid'"" and the outer rim of the ten- 
tacles, which are ferruginous. Even the space round the mouth is rust-coloured. 
The body-wall is fairly firm and provided with fine, characteristic folds, run- 
ning in a zig-zag (Fig. 23) and with minute scattered papille, presenting themselves 
as darker points (Figs. 23, 24, 25). Towards the posterior extremity the papille are 
somewhat more crowded, giving it the aspect of being sparingly villose. Exteriorly 
the surface of the skin is covered with a thin layer of a calcareous matter (Fig. 28 
cm). in consequence of which the animal, when placed in a dilute acid, rises to the 
surface of the fluid, on acconnt of the numerous bubbles of gas that arise. I have 
never seen this to be the case in other forms of Gephyrea. | 
The two ventral retractor-muscles (Fig. 26, vr) are attached to the body-wall 
about 1,> mm. in front of the posterior end of the body and at their bases the fringed 
genital bands are to be observed. 
The nervous cord runs backwards between the two ventral retractor-muscles. 
Considering that this is a rule MöBIvS” Fig. 5 must be erramneous. 
The intestinal spire is composed of sixteen twists, eight turning backwards and 
eight forwards (Fig. 26). 
The posterior portion of the contractile vessel is provided with a hundred or 
more protrusions (Fig. 27), of which the posterior ones are the longest. As a regular 
