2 Dr. R. Greeff on the Annelid Genus Spherodorum, 
liarities that may render it worth a particular description*. I 
will revert at the conclusion of my communication to the cha- 
racters common to this worm and to Spherodorum, as also to 
those by which it differs therefrom, in order the better to 
effect a comparison between them. 4 
The little animal measures scarcely 2 millims. in length, but is 
of considerable comparative breadth, attaining nearly 0-6 millim. 
in the middle regions of the body. It is narrowed before and 
behind in such a manner that the general form of the body, 
leaving out of consideration the external appendages, approaches 
an oval; nevertheless the narrowed anterior part of the body 
is shorter and more rounded, whilst the hinder part appears 
more drawn out. The skin has a general light brownish- 
yellow colour, with dark-brown marks (plaques) distributed 
singly over the whole surface of the body; these acquire the 
most various forms, and possibly represent the secretion pro- 
duced by the cutaneous glands. At no part is there a trans-- 
verse segmentation of the body indicated by external furrows. 
The segmentation, however, is sufficiently indicated by the ex- 
ternal appendages, according to which the entire body is divisible 
into 18 segments. The cephalic segment (see PI. I. fig. 1), 
which at first sight almost presents a greater resemblance 
to that of a mollusk than to that of an annelid, is the longest 
of all; its somewhat truncated frontal margin presents in the 
middle a distinct but not deep notch forming the two lateral 
lobes of the head. On each lobe are seated two clavate tenta- 
cles—cne placed more towards the upper surface, the other 
lower down towards the mouth; so that, in all, four cephalie or 
frontal tentacles are present—two superior, and two inferior. 
The bases of these, as also the space hetween them, are densely 
set with small papillee, likewise more or less clavate, which are 
distinguished from the true tentacles by nothing but their 
smaller size; so that the tentacles, from their whole habit and 
when compared with the small papille surrounding them, 
might likewise be characterized as papille projecting, in conse- 
quence of especial development, from the midst of the numerous 
smaller but otherwise perfectly similar structures. But their 
constant occurrence on the above-mentioned spots on the head, 
their size, and mobility justify their receiving the denomination 
of tentacles. 
Further back, at about half the length of the head, there are 
* I have alrecdy made a brief communication upon this subject, at 
the Meeting of the Niederrheinischen Gesellschaft fiir Natur- und Heil- 
kunde (Bonn) on the &th February, 1866, where I also exhibited ‘the 
drawings relating to it (KOlnische Zeitung, 31st March, 1866, No. 90). 
