The Ventral Armor of Dinichthys. — Wright. 317 
The facts which compel this reconstruction are as follows : 
1st. The so-called "jugulars" and the anterior ventrolat- 
erals were certainly contiguous and overlapping plates. Their 
natural relative position is that shown in plate IX, in figures 
1 to 7, in which 1, 2 and 5 represent anterior ventrals and 3, 
4 and 7 the so-called "jugulars." This relation is proved by 
the perfect fitting of the overlapping portions. Upon each of 
the "jugulars" there is a triangular, depressed area, shown in 
the upper portion of fig, 9, for the reception of an overlapping 
bone, and into this depression the thin, triangular extremity 
of the anterior ventral fits perfectly. The bones represented 
in figs. 1 to 4 are known to have belonged to a single individ- 
ual, of which the cranium, mandibles and other bones to the 
number of eighteen were found together at one time and 
place. Numbers 5 and 7 of the plate were also found together 
at a different point. Here then are three cases in which the 
perfect overlapping proves that the so-called "jugulars" were 
the companions of the anterior ventrals. The case is so clear 
that I have no hesitation in saying that this relation of the 
plates in question is demonstrated. 
2d. The "hyoid" ? bone which was figured in the mono- 
graph and believed to overlap the "jugular," is not shown to 
have the shape necessary for filling the depressed area in the 
jugular, nor is it indicated which end of the plate occupied 
this area. It is excluded from the association assigned to it 
by the facts already stated; and while it may have occupied 
a position in the hyoid region, the grounds for assigning it to 
such a position seem now to be uncertain. 
3d. The size of the so-called "jugulars" is rather large, and 
the curvature of their outline rather strong, for the position 
to which they were first assigned. In the first case here fig- 
ured (plate IX, figs. 3 and 4), the "jugulars" measure 16 inches 
in length. The curved border also measures 16 inches to the 
lateral angle, that is. along the margin which is supposed to 
have lain against the inner side of the mandible. The mandi- 
ble of the same individual, however, was only 14J inches in 
total length. Other specimens of the "jugulars" have been 
found of enormous size. For instance, one was discovered 
near Columbus, Ohio, to which my attention was drawn by 
Dr. Claypole, who kindly furnished me a tracing of it. This 
