180 KANSAS UNIVERSITY QUARTERLY. 
Contrary to anticipations there is but one predentary, as is proven 
by the discovery of all of the parts in place. It is long and slen- 
der, triangular in outline, with a broad elliptical articular surface 
at the posterior extremity. When this element was first made 
known* in this genus, I was under the impression that it was 
paired, which is not thecase. This slender projection was no doubt 
used as a weapon of offense, analogous to the rostrum of Protosphy- 
raena, In connection with the description of Saurodon broadheadit.+ 
I figured a predentary of an enterely different form from the 
above, which was found on the same slab with the maxilla de- 
scribed; the form is the same as that found in Saurocephalus. 
Whether the two bones belonged to the same individual or not, 
only future discoveries can determine. After carefully comparing 
the type of S. dentatus with that of the species under consideration 
and SS. fevox, 1am convinced that there is but one predentary in the 
mandible of this form, as one would expect from the great simi- 
larity of the two genera. 
MEASUREMENTS. 
mm 
Manaibleslength fromycotyloidcavityss. jaa. e oe ae eee cee eee 155 
i depth: atisymphysis .40 27.1 As sey nash ORME eee ont eat Ge ee 23 
: number of:teethy dino 562 mae hee Sao eect iy Bier ema ire ole ae 4.5 
Predentary.; sleng these ete ee 20 Ae ean it a Renta Ee yee ee ee a 734 
depth of symphiysealisurtaces jen passer tree content rene 23 
st width’, of /symphyseal'sutiaoe¢ 2). eS eats pitta tener 12 
The ethmoid is broad and flat posteriorly, becoming thickened 
and pointed at the anterior extremity. The lower surface can not 
be seen, but it probably is not materially different from that of 
Ichthyodectes. In Prof. E. T. Newton’s description of .S. znterme- 
dius\| he says, concerning this part; ‘‘Anterior to the frontals, upon 
the upper surface of the skull, there are two bones (fig. 2) sepa- 
rated by a median longitudinal suture; towards the front of these 
an osseous band passes across at right angles, obliterating the 
suture.”’ In our skull I am unable to detect any indication of a 
suture at this point such as is shown in the figure referred to above. 
I have also examined all of the specimens of Azphactinus and 
Ichthyodectes in the museum, and find no trace of such a suture in 
any of them. It seems probable to me that the skull, described by 
Prof. Newton, was a younger individual than are any of ours. 
*Kans. Univ. Quart., vol. vii, p. 24. 
+15... spl. 1: 
tEstimated. J 
!Quart. Journ. Geol. Soc., vol. xxxiv, No: 135, p. 444, pl. xix. 
