ITS STRUCTURE, BULK, AND ASPECT. 97 



ceedingly common one during both the Palaeozoic and Se- 

 condary periods. It has left its impress on all the better pre- 

 served coprolites of the Coal Measures, so abundant in the 

 shales of Xewhaven and Burdie House, and on those of the 

 Lias and Chalk. It seems to be equally a characteristic of 

 •well nigh all the bulkier coprolites of the Old Red Sandstone. * 

 In these, however, it manifests a peculiar trait, which I have 

 failed to detect in any of the recent fishes ; nor have I yet 

 seen it indicated, in at least the same degree, by the Carboni- 

 ferous or Secondary coprolitic remains. In the bowels which 

 moulded the coprolites of Lyme-Regis, of the Chalk, and of 

 the Newhaven and Granton beds, a single screw must have 

 winded within the cylindrical tube, as a turnpike stair winds 

 within its hollow shaft ; and such also is the arrangement in 

 the existing sharks and rays ; whereas the bowels which 

 moulded the coprolites of the Old Red Sandstone must have 

 been traversed by triple or quadruple screws laid closely to- 

 gether, as we find the stalk of an old-fashioned wine-glass 

 traversed by its thickly-set spiral lines of thread-like china. 

 And so, while on the surface of both the Secondary and Car- 

 boniferous coprolites there is space between the screw-like 

 lines for numerous cross markings that correspond to the 

 thickly-set veiny branches which traverse the sides of the re- 

 rent placoid bowel, the entire surface of the Old Red copro- 

 lites is traversed by the spiral markings. Is there nothing 

 strange in the fact that, after the lapse of mayhap millions 

 of years, — nay, it is possible, millions of ages, — we should be 

 thus able to detect at once general resemblance and special 



* In two of these, in a collection of several score, I have failed 

 to detect the spiral markings, though their state of keeping is de- 

 cidedly good. There are other appearancies which lead me to suspect 

 that the Asterolepis was not the only large fish of the Lower Old 

 Red Sandstone ; but my facts on the subject are too inconclusive to 

 justify aught more than sedulous inquiry. (First Edition. See Note^ 

 p. 92.) 



Q 



