50 The American Geologist. J'^''- ^''"^• 
And it is these features, in fact, that have furnished the basis 
of later discussion. 
One naturally reasons, a priori, that the key of the puzzle 
of Menaspis will be forthcoming when abundant and better 
preserved specimens are secured. But this reflection gives 
little comfort when for a decade no satisfactory material has 
been brought to light. There is thus, as far as I am aware, 
but a single additional specimen to be drafted into the dis- 
cussion. This, it may be mentioned, has been secured bv the 
Prussian pal^eontological museum. And it is primarily from 
the examination of this specimen which, thanks to the courtesy 
of i^rof essor Jaekel, the present writer had the privilege of 
examining during a recent visit to Berlin, that the following 
notes are suggested. 
The undescribed specimen is of especial value since it pre- 
serves the dental plates. And from the size of these elements 
one is led to conclude that the head could not have been en-- 
closed within tlic region suggested by earlier aiithors, and 
that, accordingly, the posterior spines, hitherto regarded as of 
the hinder trunk region, mark in reality the region of the oc- 
ciput. This view is indicated in the accompanying restoration, 
Fig. lA, which has been based upon a combination of the 
contours of the earlier and newer specimens. Confirming this 
view, moreover, is the presence of the mucous canals alreadv 
described in Jaekel's (1891) paper. Two of these are present 
on either side of the head. Fig. lA, il/C, one representing the 
frontal canal, the other the supraorbital. Two additional 
points strengthen the newer interpretation, first, the presence 
of shagreen tubercles lying at the side of the fossil, as pictured 
by Jaekel, and second, the position of the bases of the fins, as 
also given in the cited work. In the first regard, it may be re- 
called, Jaekel maintained that these shagreen plates are widely 
displaced, having been crushed into a lateral position during 
the process of fossilization : according to the present interpre- 
tation, these plates, Fig. lA, L S, remain in approximatelv 
their normal position, as the only remnants — somewhat denud- 
ed, but corresponding in arrangement with those on the op- 
posite side of the body — of the armoring of the trunk pre- 
served on this side of the fish. In the second regard, it will 
be seen that the pectoral fin is in its usual position with respect 
