KUNGL. SV. VET. AKADEMIENS HANDLINGAR BAND 39. N:o l. 11 
Tentaeles. digitiform or else in the shape of a lobed membrane, always surround the 
mouth. Except in a single specimen hooks are absent. Mostly two contractile vessels. 
One or more divertieles on the rectum, simple or branched. Alimentary canal coiled 
to a true spire with or without a spindle-muscle. 
KOREN and DANIELSSEN obtained by dredging and deseribed two, as they assert, 
different species of this genus. For reasons given further on I am of opinion that 
we have here to do with only one species. DLRVINSEN' has founded a new genus, 
Phallosoma, comprising these two species. However, I must confess that I do not 
quite understand his views on this point. In 1883 SELENKA directed attention to two 
groups of Sipunculus devoid of hooks, the one provided with tentacles in the shape 
of a lobed membrane and with two vessels, the other having the tentacles digitiform 
and possessing a single vessel. Nevertheless, he does not insist on referring them to 
different genera. KOREN's and DANIELSSEN'S form, or forms, indisputably belong to 
the "nudus-group and, supposing there exist some reasons for dividing the old genus 
into two or several, I think it most correct to save Linnés name "Sipunculus' for 
this group. 
Phascolosoma F. S. LEucCKART” 1828. The followimg remarks may be added to 
the Synopsis. Tentacles, more or less numerous, arranged in one or more rows, or 
else im groups, surrounding the mouth. In several cases they are totally reduced. 
Hooks present or not. A couple of ciliated sense-pads outside the brain. One con- 
tractile vessel generally present. Alimentary canal forming a spire, mostly provided 
with a spindle-muscle, not attached to the posterior extremity of the body. Two 
dorsal and two ventral retractors, or two ventral ones only. The genus Phascolosoma 
is more richly represented in the northern and aretic seas than any other genus. It 
comprises about 14 species, several of which, however, may be looked upon as rather 
dubious. In conformity with my own views of 1875 and those of SELENKA of 1883, 
but contrary to those of KOREN and DANIBELSSEN, I have eliminated such forms as 
ought, on account of their deviating organisation, to belong to the genus Phascolion. 
Moreover, I have carried over the Phascolosoma squamatum of KOREN and DANIELSSEN 
from this genus to the genus Oncehnesoma of the same authors. On the other hand, 
I have incorporated with it the genus Stephanostoma of the same Norwegian investi- 
gators and two of their Onehnesoma-species besides. The reasons are given further on. 
ÅAspidosiphon. DIESING 1851”. Considering that sufficient characteristics are already 
given in the Synopsis, I have here only to add that the proboscis is eccentric and 
ventral in position to the anal shield, that the digitiform tentacles surround the 
mouth, except on a ventral space, and that some very rare exceptions from the rule 
exist with regard to certain organs in some exotic forms. Two ventral retractors. 
2 (Of Oh 
? Breves- animal. descript. Heidelberg. 1828. 
> Systema Helminthum. Vol. II. Vindobonge. 1851, pp. 67—68. 
