244 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 5, 



towards it, as if from want of muscular power, and to have been then 

 renewed again with fresh vigour * ; and a corresponding difference is 

 observable in the strength of the median track, as if the body had 

 been elevated and depressed at intervals. 



We have only traces of three of these successive, and, so to speak, 

 spasmodic attempts at progression in what was probably very shallow 

 water, scarcely deep enough to float the animal. In the lower or 

 first group there are six pairs of larger imprints, gradually coming 

 nearer to the central line, and somewhat closer also to each other ; — 

 then a small one, c, which may have been a point of rest, much nearer 

 to the groove than the others : the eighth pair suddenly starts out 

 again, and with a breadth equal to those of the first set, and four, or 

 probably five strokes of this series were given before the line of pro- 

 gression, having swerved a little from the original direction, was re- 

 newed again, somewhat to the left, aty, where we have only the central 

 groove and a single pair of imprints, the rest being lost. 



The whole would be consistent with the action of a single pair of 

 swimming limbs, and the impression of a pointed or ridged sternal 

 portion, but does not, I think, favour the supposition of a long body 

 with a pointed caudal segment, such as Hymenocaris or Eurypterus 

 possessed. — J. W. Salter.] 



At Binks also there are seen on the strata some branching bodies, 

 which from their indeterminate form must at present be referred to 

 that division which includes most indistinct organic bodies, viz. 

 Fucoids. 



Organic remains are not, however, restricted to this locality among 

 these very low strata of the Lower Silurians of the South of Scotland. 

 Fossils are found in the reddish-purple shales, which have been al- 

 ready alluded to as occurring, along with the thin grey shales and thin- 

 bedded greywacke-sandstone (as developed in the parish of Apple- 

 garth at Upper Cleugh Burn, on the south side of the axis) . These 

 fossils consist of Protovirgularia, which was first discovered in this 

 spot last year by my friend Sir William Jardine, and also some small 

 branching bodies, which appear to bifurcate dichotomously, and have 

 somewhat the character of branching Graptolites of the genus Didy- 

 mograpsus. These were met with by the late Prof. E. Forbes and 

 myself, in the same reddish-purple shale which affords Protovirgu- 

 laria, in the autumn of 18.54. They are, however, too indefinite to 

 admit of their being assigned to any known forms. 



Graptolites also occur on the south side of the axis at Dalton 

 Rocks in the parish of Dalton, Dumfriesshire ; and these, from their 

 relative breadths, seem to belong to two species. They are, how- 

 ever, in too imperfect a state to allow of their being referred to any 

 particular species. They are met with in a shaly bed, associated with 

 greywacke-sandstone very distinctly rippled ; deposits very different 

 from those which contain these fossils elsewhere in Dumfriesshire. 



On the south side of the axis, in this county, we have no traces 



* Or it may be, as kindly suggested to me by Prof. Owen, that the body was 

 elevated by the successive strokes, and the feet consequently touched the ground 

 nearer to the central line. — J. W. S. 



