336 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [JuHO 19, 



from the shore, twice obstructed by the forward wash of the surf, 

 which stranded it again. The tracks A and B are exactly similar, 

 except that one is deeper than the other, and the imprints are at 

 unequal distances ; and they have every appearance of being made 

 by the same individual. But the difference in depth of the three 

 tracks shows clearly the direction to have been from A to A*, or the 

 reverse ; and it will be observed that this line of direction is trans- 

 verse, but a little oblique also, to that of the linear imprints them- 

 selves. 



The more confused slab (fig. 2) shows none of these points so 

 strongly ; but is easy of interpretation by the help of the more per- 

 fect one ; and the evidence of the two together is conclusive on one 

 point — namely, that the successive imprints were made in solitary 

 lines, and are not the results of a track of any animal with nu- 

 merous appendages. 



Our attention is therefore limited to the possible nature of the 

 organ or organs which could produce a transverse (slightly oblique) 

 bilobed or double impression at each stroke, at intervals of about an 

 inch. 



The most perfect of these imprints are | of an inch long, not quite 

 I of an inch broad, and about a line deep in their strongest im- 

 pression. They are slightly curved, deepest forward on the inner 

 side of the curve, and sloping behind. I take the direction of the 

 track to be from A to A*. 



Each imprint is double ; and on slab 1 the longer and shallower 

 lobe is on the right, the deeper and shorter lobe on the left ; and 

 behind this shorter lobe, at a distance varying from one to two lines, 

 is a shallow pit, in the same direction as the main imprint, and a 

 little wider than long. These supplementary imprints are wanting 

 behind most of the shallower main impressions. 



Between the two lobes of the imprint the sand is always more or 

 less pinched up, as if the action had been (and I believe it was so) 

 from without inwards. It is as if a pair of rude blunt forceps had 

 been used, whose arms were occasionally of unequal length. Some- 

 times, as at X in fig. 2, the points of the forceps have not met 

 closely, one being a little behind the other. This character, however, 

 is rare, though seen on both slabs ; while the appearance of a 

 pinching action is visible on most of the imprints in each case. 



In one, or possibly two instances (y, fig. 2), there is a short return 

 stroke, as if the forceps, after meeting near the centre, where the 

 deepest indent is made, had escaped in a somewhat different direction. 

 In this case the lobes or strokes are equal, and there is no supple- 

 mentary impression. More commonly stiU, two short punctures in 

 the sand, a line or two apart, are equal in strength ; and in these 

 instances, again, no supplementary indentation has been made. 



Lastly, on the larger slab are several examples in which the sand 

 has been heaped up on one side or the other, or even hetween the 

 imprints when the stroke has not closed, as if the instrument on 

 leaving the surface had driven the sand forcibly outwards. 



Single indentations occur ; but the double ones are so much more 



