357 
of Edinburgh, Session 1876 - 77 . 
of these closely related forms, being unisulcus, destitute of striae, 
and not more than three-eighths of an inch wide, while all these are 
striated and seven-eighths of an inch wide ; that under notice being 
moreover distinctly bisulcate. It is acknowledged that the relations 
of this to recent forms are obscure. The features which chiefly 
claim attention are— 
First, The outline of the animal. — A glance at the specimen 
is sufficient to convince us that we have here not a track merely, 
but the representation of an annulose form. (See Plate IY. fig. 1.) 
On one of the slabs this is associated with several inches of 
the track over which it has passed. The median dorsal line 
is fully exposed above, while the median ridge, which makes 
the track bisulcate, is precisely what would be formed by the 
ventral groove of a nereis — Alitta virens (Sars), for example. 
The striae which pass round the body leave no traces of their 
outline in this track ; but in another, from which the repre- 
sentation of the animal was removed, these striae are well marked. 
Again, on the bulged sides of the tortuous outline, the striae 
are wider than on the opposite side, while in the comparatively 
straight parts they are symmetrical. So far as I know, similar 
markings do not occur on any recent annelid. They are, however, 
represented, though not so distinctly as here, on a small annelid — • 
Epitrachys rugosis- — figured by Ehler of Erlangen in his paper on 
the “ Fossil Worms of the Lithographic States of Bavaria. 1 ”* 
Second , The tracks.— They differ widely from the tracks both of 
mollusca and Crustacea— those of the former being, for the most part, 
sharp in their turns, and those of the latter consist generally of 
lines more or less straight, not tortuous. In addition, they have 
two furrows divided by a distinct median ridge. I am sure that 
had the able observers named above seen such specimens of the 
tracks, and also of the intaglios of the rounded dorsal surface as are 
now on the table, they would not have questioned the true annulose 
character of this organism. 
Third , The median dorsal line.— This is exceedingly well repre- 
sented, not only on the outline of the animal itself, but also in one 
of the intaglios referred to. It consists of small, shallow, oval 
* Ueber fossile Wurmer aus dem lithographischen Schiefer in Bayern 
Cassel, 1869. 
