328 DR RAMSAY H. TRAQUAIR ON FOSSIL FISH-REMAINS 



In fig. 2 we have the counterpart of the above-described fragment, which shows a 

 slightly larger extent of surface. In the central area of the plate the bone has adhered 

 closely to the matrix, so that the impression of the sculpture of that part is shown only 

 along a narrow portion on the right side ; and here, as noted above, the ridges become 

 oblique and irregular as compared with their tolerably close parallelism in the marginal 

 band. 



In fig. 3 we have another fragment of quite an irregular shape, namely roughly 

 triangular, and measuring 6 inches in greatest length by 3^ in greatest breadth. 

 Of the three margins, one (the lower in the figure) is nearly straight and may 

 well be considered to have been an original margin, as also may the shorter irregular 

 one on the left side ; while the remaining border marks, of course, the line where the 

 plate is cut off by the edge of the stone. 



Like the previously described plate, its surface is proportionally thin, its thickness at 

 the thickest part being only ^ of an inch. Only towards the short margin is the ex- 

 ternal sculpture shown, and this consists mostly of comparatively coarse, plain, reticulat- 

 ing ridges, which become finer towards the margin of the plate, and there exhibit 

 evident traces of a beaded ornament similar to that which has been noted in the first 

 described specimen. 



As the above described two pieces are mere fragments, it is scarcely possible to locate 

 them accurately on the body of the fish. I should, however, be inclined to suppose that 

 the first (figs. 1 and 2) belonged to the ventral carapace, and is in fact a fragment of the 

 anterior or posterior part of the anterior ventro-lateral plate marked b x in text-figure 3. 



Observations. — The sculpture of the first described specimen, which shows promi- 

 nently a marginal band of ridges nearly parallel with each other and nearly at right 

 angles with the edge of the plate, together with the great proportional thinness of the 

 bone, indicate Holonema of Newberry as the genus to which it ought to be referred, 

 while the beaded ornament of the ridges supplies us with a tangible specific mark. As 

 regards the second example, we note first, that although the marginal band of parallel 

 rugge is not visible, owing to the surface of the bone along nearly the whole of the long 

 margin having come away with the counterpart, yet the distinct occurrence of the 

 minute bead-like tubercles on some of the finer reticulating ridges which are exposed 

 indicates that this second plate belongs to the same species as the first. 



Locality. — Bressay, near Lerwick, Shetland ; collected by Dr J. S. Flett. 



Undetermined Fragments. 



The residue of the collection consists of fragmentary dermal plates of fishes, which 

 are really unnameable, as their contour affords no clue to their original shape, nor is 

 there anything in their sculpture of a really determining character. Of these I have 

 figured three examples. 



Fig. 5, PI. I., is an angular fragment showing two overlapped facets and a large 



