48 0. C. Marsh on a new species of Protichnites. 
seen if atall. The footprints indicate, moreover, a muchsmaller 
animal than those which made the other orms of rotichnites, 
the width of this series ig ae in general less than one hal 
that of the other species, excepting P. multinotatus, from 
which, however, it differs in the absence of the medial groove, 
and in the less numerous, and more irregular footmarks. 
The margins of the individual impressions are not in most 
instances accurately defined, partly perhaps owing to the fact 
that the surface of the sandstone has been somewhat worn b 
the water and ice of thelake. In this way some of the smaller 
impressions may have been obscured or obliterated, as it is now 
pisces to trace with certainty through the whole series the 
s of footprints which correspond to the repeated ap- 
ficctione of the same limbs of the animal; although such 
a repetition is easily recognized where the tracks are best pre- 
served. In such places the i impressions are seen to be arranged 
in groups of six, which in each row evidently represent succes- 
sive applications of the same series of limbs, the corresponding 
set on the other sige making a group ne arly or quite opposite 
when the animal moved directly forward, but partially alternat- 
ing when it turned to the right or left. Each group appears to 
consist of four impressions in the direct linear series, and two 
additional ones inside, and a little behind the last two. The 
ea a of thei impressions thus produced probably indicates, 
rof, Owen has shown in regard to the other species, the di- 
reason in which the animal was moving. 
The bottoms of some of the tracks are sharply defined, and 
were evidently impressed by hard pointed limbs. This would 
show conclusively that they were not made by a Trilobite, to 
which their origin might otherwise naturally be attributed ; 
while the absence of a medial groove would probably exclude a 
Crustacean of the type that made the other Protichnites. The 
points of pte between this species and those hitherto de- 
scribed ently marked to justify its separation, and it 
may very Sppipriaicly be named, Protichnites Logananus, in 
honor of Sir Wm. E. Logan, Director of the Canadian Geol-_ ; 
oe Se Survey, to whom this branch of paleontology isso much 
indebte . 
e peculiar interest attached to these various footprints on 
the oldest Silurian strata depends i in part upon the fact, that we — 
thus have evidence of forms of life before unsuspected ; since 
no other indications of the animal that made them have as yet 
been ban Gi An e aie ik should perhaps be made of 
