328 NEW YORK STATE MUSEUM 
The second specimen, a fragment of an endognathite, which passed 
from the Miller collection into the Faber collection, and finally into the 
Walker Museum at Chicago University, probably is another fragment from 
the same individual. Judging from its size, it may represent the three 
joints preceding the terminal joint of one of the endognathites. In that 
case, the. presence of the large spme and apparently also of a small spine 
along the distal margin of this fragment is noteworthy. As a matter of 
fact, the relative position of this fragment in the endognathite is unknown. 
The third specimen, also formerly in the Miller collection, but now 
in the Faber collection in Walker Museum, is the dorsal side of one of 
the postabdominal segments. This position is indicated by its con- 
siderable length, compared with its width. The surface is ornamented 
by numerous scalelike markings, the raised border of which is directed 
toward the posterior extremity of the animal. Most of these mark- 
ings are oval in form but along certain lines parallel to the length of 
the animal, they are more nearly oblong or linear in shape. ‘These rows 
of linear scalelike markings unquestionably were more or less in line with 
similar rows on preceding and succeeding segments. Along these lines 
the segments were slightly elevated. These lines of scalelike markings 
and the slight elevations upon which they are found are at least four in 
number, and are separated by spaces 14 or 15 mm in width; they 
extend only along the posterior half of the segment at hand. Near the 
anterior extremities of these spaces, the surface of the segment is marked 
by irregular, shallow, anastomosing lines or depressions which may be due 
in part to compression after the death of the animal. 
The endognathite first described bears a considerable resemblance 
to that figured by Woodward in his Monograph of the British Fossil Crus- 
iacea of the Order Merostomata as Eurypterus punctatus. It 
does not possess the long backward curving spinesof Echinognathus 
clevelandi Walcott, now in the possession of the National Museum.. 
Remarks. Asin Echinognathus clevelandi, the frag- 
ments of Megalopterus are not sufficient for a determination of either 
identity with or differentiation from the Upper Siluric genera, and the 
generic name 1s principally the expression of supposed generic distinction 
based on the Lower Siluric age of the organism. But there stand out a 
few characters which clearly suggest certain taxonomic relations of the 
form with the later genera; and these are so similar to those of Echinog- 
nathus that they indicate either close relationship or identity in these 
two Lower Siluric eurypterids. These characters are: the multispinous 
