THE OLD RED SANDSTONE. 169 
was fortunately led to discover them anew in her possession. 
The most abundant organism of the group was a variety of 
Pierichthys — the sixth species of this very curious genus now 
discovered in the Old Red Sandstones of Scotland ; and as the 
Docto1 had been lucky enough to find out for himself, some 
years before, that the scales of the Holoptychius were oyster 
shells, he now ascertained, with quite as little assistance from 
without, that the Pterichthys must have been surely a huge 
beetle. As a beetle, therefore, he figured and described it in 
the pages of a Glasgow topographical publication — Fife Il- 
lustrated. ‘True, the characteristic elytra were wanting, 
and some six or seven tubercle plates substituted in their 
room ; nor could the artist, with all his skill, supply the crea- 
ture with more than two legs; but ingenuity did much for it, 
notwithstanding ; and by lengthening the snout, insect-like, 
into a point — by projecting an eye, insect-like, on what had 
mysteriously grown into a head — by rounding the body, in- 
sect-like, until it exactly resembled that of the large “ twilight 
shard” — by exaggerating the tubercles seen in profile on the 
paddles until they stretched out, insect-like, into bristles — 
and by carefully sinking the tail, which was not insect-like, and 
for which no possible use could be discovered at the time — 
the Doctor succeeded in making the Pterichthys of Dura Den 
a very respectable beetle indeed. In a later publication, an 
Essay on the Geology of Fifeshire, which appeared in Sep- 
tember last in the Quarterly Journal of Agriculture, he states, 
after referring to his former description, that among the higher 
geological authorities some were disposed to regard the crea- 
ture as an extinct crustaceous animal, and some as belonging 
to a tribe closely allied to the Chelonia. Agassiz, as the 
writer of these chapters ventured some months ago to pre- 
dict, has since pronounced it a fish —a Pterichthys specifica'ly 
tT a 
