30 
Before leaving the head I will mention some peculiar formations, which I am at a loss 
to understand. In Spher. frontalis we notice at the middle of the frontal margin (pl. VIII, 
fig. 1d) a strange cup-shaped, rather large expansion in which I have been unable to find any 
hole which might be the outlet from some gland. In Spher. modesta, on the ventral side of 
the protruding frontal border, inside its margin we see a square of considerable size (pl. LX, 
fig. 2d, x) with rounded corners, which seems to be pierced with rather numerous holes. 
The Trunk. The body — except the head — of course corresponds to thorax and 
abdomen, but in the three genera treated here, the latter never appears as a separate part; 
we must consider it as being represented by the genital area and its surroundings, which, 
however, are not marked by distinct outlines. I beg to give notice that, as a separate 
abdomen only appears in the genus Stenothocheres (s. below) and in no other genus of the 
whole family, I shall — for practical reasons —in mentioning and describing all the genera, 
except Stenothocheres, always both here and in the systematic part use the word »trunk« for 
the whole body, except the head. 
The shape of the trunk is mentioned above, for as the head, at least in adult spe- 
cimens of most species, is very small, I can refer to my description of the body (p. 24—25). 
The skin — except on the genital area —is very thin, often quite naked, sometimes covered 
with hairs behind the head, being naked everywhere else, sometimes hairy all over. In several 
species the trunk is more hairy during the early, not half-developed stages, than when the 
animals have grown to their full size, so e. g. in Spher. danica, whose young ones are covered 
all over with peculiar thin, flat hairs, whereas the older specimens are either quite naked or 
have only a hairy part behind the head. In Spher. Calliopii (pl. I, fig. 3d and fig. 3g) the 
trunk has a rather close coat of very peculiar three-branched hairs growing out from tiny 
knots, the middle hair being longer than the two others. In Spher. irregularis (pl. XII, 
fig.5¢ and fig. 5d) somewhat similar two- and three-branched hairs are seen. 
In most species the trunk has two pairs of entirely uniform legs, but in a good 
number of species (as in Spher. microcephala, and in all eight species of the Spheronella living 
on Cumacea and Isopoda) legs are entirely wanting. The legs are placed on the ventral 
side, now at some distance within the outline, now at the lateral margin, and as a rule there 
is no considerable difference in the distances between the first pair and the head, between 
the first and second pairs and between the second pair and the leg-like caudal stylets. In 
Homoeoscelis the legs, though small, are comparatively conspicuous, each apparently consisting 
of a diminutive, short and rather thick basal part, from which proceeds a much longer, very 
narrow, conical, almost setiform branch and a pair of very short bristles or a short tap as 
an indication of a second branch. In Spheronella and Choniostoma the legs are nearly always 
exceedingly small; in recently hatched or young specimens they are as a rule easy to find, 
but as they do not grow, they are often very difficult to point out in adult animals. Hach 
leg consists of a small cylindrical joint ending in two short sete. In Spher. longipes (pl. VU, 
fig. 2a and fig. 2e) only, the legs are somewhat larger, particularly because one of the sete 
