A NEW FORM OF “DIPLOCAULUS” 51 
quadratojugal near the mid-length of the horns on their under- 
side apparently forms the anterior border of an opening for the 
entrance of water into the gill chamber. In most Dipflocaulus 
skulls there is a depressed area along the quadratojugal-squamosal 
union which increases in depth toward the notch, possibly to direct 
water into the opening. In the specimen herein described the 
notch is unusually pronounced and the depression leading to it is 
longer, deeper, and more nearly smooth than is commonly noted. 
THE VERTEBRAE 
The real interest in the material centers in the vertebrae, 
especially in their exceptionally large size and in the development 
of the neural spines. While there is no means of determining 
accurately the position of the series in the vertebral column, it 
is assumed that they are from the anterior end, very likely numbers 
3 to 11. The first of the preserved series is somewhat shorter 
than any that follow and it alone has a conspicuous lateral expan- 
sion of the neural spine, a condition that suggests its proximity 
to the skull. Furthermore, this vertebra is the only one of the 
series that lacks the characteristic pit in the top of the spine, a 
feature more or less well developed in all the anterior vertebrae 
except in numbers 1 and 3 in several specimens of the described 
types examined by the writer. 
The string of nine connected vertebrae measures about 354 mm. 
While this length is made up in a small part of matrix separating 
the centra, the figure serves well for comparison of this with pre- 
viously described forms of Diplocaulus. The average length of 
a like number of vertebrae from the same region of the column 
in several specimens in Walker Museum is but little more than 
half that given above. All other dimensions of the vertebrae 
herein described are correspondingly large. So striking is the 
size that were it not for the fact that in nearly every other detail 
the vertebrae are those of the typical Diplocaulus there might be 
some doubt as to their identity. 
In length the centra increase from about 25 mm. at the anterior 
end of the series to 40 mm. at the posterior end. The greatest 
increase is between the first and second, an increase of 5mm. 
