Mr. A. Hancock on Vermiform Fossils. 445 



Shields, and Whitburn. In these localities they are to be seen 

 everywhere between tide-marks, but are most numerous about 

 half-way down the beach, on inclined, oozy, glistening spots, 

 where the sand is firm, and yet the moisture so profuse that it 

 mirrors the light. 



In such situations they are very numerous and complicated. 

 There are two or three species, the largest (PL XIV. fig. 1) of 

 which is about three-eighths of an inch wide; it is slightly 

 raised above the general surface of the beach, and is of a flat- 

 tened, ribbon-like form, with a narrow median groove (a) run- 

 ning from end to end ; it is occasionally several feet in length, 

 winding in a very intricate manner, and is frequently and irre- 

 gularly convoluted, forming, as it were, loose knots or systems 

 in which neither the commencement nor the termination can be 

 easily detected, and which are usually connected together by 

 lengthened, slightly undulated portions of the track. The wind- 

 ings are, for the most part, well rounded, and in their course 

 occasionally, but rarely, exhibit inconspicuous, arched, transverse 

 ridges (c). The tracks also occasionally show enlargements 

 placed at some little distance from each other (fig. 2 a) ; when 

 this is the case, there is no median groove. Another variety 

 occurs, but not frequently, in which there is neither groove nor 

 nodulous enlargements. The extent and complication of the 

 windings vary considerably ; and though they are for the most 

 part exceedingly intricate, as above described, they are at times 

 found of much less extent, and comparatively simple, so that 

 they can be followed easily enough throughout their sinuosities. 

 At other times they may be seen, as it were, entirely unravelled, 

 running a considerable distance in an undeviating or only slightly 

 tortuous line. 



Besides the above, another kind of track, also very abundant, 

 is found on our shores ; it is, however, very different in character, 

 and is much smaller. It (PL XV. fig. 1) is in the form of a 

 narrow wedge-shaped furrow (a), about two-tenths of an inch 

 wide, with the margins occasionally a little elevated (b, b). Its 

 windings are very capricious, irregularly rounded, frequently 

 abruptly angulated, and sometimes for a considerable distance 

 finely and regularly undulated or zigzagged (fig. 2). This 

 species is often found in close proximity to the broad form pre- 

 viously described; but occasionally it occurs high up on the 

 beach, and in pools and small hollows between the ripple-ridges. 

 In such situations, however, it is not confined to the bottom of 

 the hollows, but likewise passes up the sides of the bordering 

 ridges. 



A third variety (fig. 3) is occasionally seen, much resembling 

 the last both in size and windings ; but the furrow (b) is smaller 



