MECZNIKOW, ON ICHTHYDIUM, ETC. 201 
As to the systematic position of this animal, through our 
incomplete knowledge of it, it is difficult to say much. It 
seems to me possible that the Echinoderes represents the 
larval condition of a perhaps unknown creature. At all events, 
the independence of this animal can scarcely be proved. 
This much is certain, that the Echinoderes bears no remark- 
able relationship to the Ichthydina, as M. Schultze believes, 
and still less to Nematodes, as Ehlers maintains. 
IIT. ConcerNING THE OUTSIDE STRUCTURE OF DesMoscoLex. 
—After having spoken of a very little known animal, I will 
now pass on to a still less known one, which was discovered 
by Claperéde, and named by him Desmoscolex minutus, 
which I have found in Heligoland. This animal possesses, 
besides the head, eighteen strongly chitinised brown-coloured 
rings, which are separated from one another by pale elastic 
spaces. From the brown rings (the head being omitted) 
spring peculiar tubercles, which Claperéde considers to be 
compound Annelid bristles, and which he has used for 
the foundation of his ideas on the zoological nature of these 
animals. But the closer examination of these bristles allows 
us to contradict the idea of Claperéde. Each such bristle 
forms an uninterrupted continuation of the segment ridge 
itself, and is not therefore planted in the space of the same, as 
is the case with Annelid bristles. To this may be added that 
the somewhat crooked and tapering bristles show in the 
inside a fine canal, and pass at their end to a fine flat point, 
which must be considered as a particular part of the bristle, 
but which at the same time can give no foundation for a com- 
parison with a compound Annelid bristle. Both parts ‘stand 
in uninterrupted connection with one another, and therefore 
present a form which I consider as a sensitive hair, and would 
in a certain sense compare with cirrhi and tentacular cirrhi. 
After my description and elucidation of the bristles, their 
position on the head will lose all that is paradoxical. Besides 
the four head bristles, Claperéde describes in his species 
others which are placed on each side of the second, fourth, 
sixth, eighth, &c., segments. This description does not 
entirely agree with his drawing, where there is no bristle to 
be seen at the sixteenth segment, but where on the other 
hand the following segment is provided with four. 
In on species—if it represents a new kind at all—the position 
of the bristle is still more peculiar. Our animal bears through- 
out, besides the four head bristles already known, one pair 
on each segment (with exception of the eleventh and fifteenth). 
One of the bristles lies in the median line of the animal in the 
