ON CERTAIN VERMIFORM FOSSILS. 29 



closely resembles those of the crustacean as scarcely to leave 

 room for the interrogation, — of what ? It is hardly to be 

 doubted that they belong to some animal of that class. 



From the above observations we seem justified in concluding 

 that these curious vermiform fossils are the tracks of crustaceans ; 

 but before doing so, it would be well to inquire how far they are 

 likely to be the remains or tracks of worms, or worm-tubes, or 

 any other organic body. In the first place, the enormous length 

 of the grooved and nodulous forms is rather opposed to their 

 being the remains of worms. Of course this does not militate 

 against their being worm-runs, though the great width they 

 sometimes attain does not at all favour that opinion. The width 

 of the largest specimens of the grooved form is a little over an 

 inch, and of the nodulous species about half-an-inch ; their length 

 may be three, ten, or twenty times greater than the measure- 

 ments before given, as none of the larger specimens, as already 

 stated, have yet been obtained with both extremities perfect. 

 Size alone, however, is not sufficient to debar the possibility of 

 their having been formed by worms ; but upon such a hypo- 

 thesis how are we to account for the peculiar character of the 

 nodulous form ? It is impossible to comprehend how the nodules, 

 which are imbricated, passing diagonally through the track, 

 could have been produced by a worm working its way through 

 sand, mud, or any other material whatever. With respect to 

 the grooved form it may also be asked, do worms or any of the 

 annelides ever make runs at all similar to it ? I know of no in- 

 stance of any of these animals making a tunnel-track immedi- 

 ately beneath the surface of the beach, confined to the same 

 horizontal plane, and with an elevated, arched roof. Annelides 

 do not move along the surface in this manner, and when they 

 burrow they dip downwards, making perfectly circular passages. 



The small furrowed kind, for size, might very well be the 

 track of some worm, but its close resemblance to the runs of 

 crustaceans has already been pointed out. With regard to the 

 small cylindrical runs not much can be said, as they are too de- 

 ficient in character to allow of any very decided opinion, only 



