MOODIE: MAZON CREEK, ILL., SHALES. 337 
caudal ribs. It is not so readily separable from the Branchio- 
sauria of Europe. It is most closely related to Branchiosaurus 
amblystomus Credner of the Permian and Carboniferous of 
Saxony. From this genus, however, Mazonerpeton may be 
distinguished by the reduction of the posterior tympanic 
notch, the broad nature of the scapula, the elongate inter- 
clavicle and the slender ilium in the present form. The num- 
ber of dorsal vertebre is identical in the two genera. 
The genus is so closely allied to Branchiosaurus of Europe 
that the two species here described must be located in the 
family Branchiosauride. 
Mazonerpeton longicaudatum new species. 
(Plate 3, figs. 1 and 2; plate 7, fig. 3; plate 10.) 
The remains on which the above species is based consist of 
the following elements: an incomplete skull, nearly the entire 
vertebral column, consisting of cervical, dorsal, sacral and 
caudal vertebre, 36 in number; several ribs preserved on 
each side of the vertebral column, a portion of the ventral 
armature, the scapule, a clavicle, the interclavicle, both hu- 
meri, the radius and ulna of one side and the ulna of the other, 
portions of both hands, the ilium of the right side, both 
femora, and a partial impression of the left tibia. 
The skull is unfortunately very poorly preserved. Enough 
remains, however, to determine the essential characters. The 
skull bones, unlike any other American branchiosaurian, have 
an ornamentation consisting of sharp pits and elevations, 
which in places have a quincuncial arrangement and in others 
take the form of definite lines of pits or tubercles similar to 
the condition found in many of the Microsauria. The orbits 
are large and are situated back of the median transverse line 
of the skull. They are almost circular in form and contain 
six elongated sclerotic plates very closely arranged around 
the borders of the right orbit. The plates are twice as long as 
wide. The interorbital width is one and one-fourth as great 
as the transverse diameter of the orbit. 
Not many of the sutures of the skull are discernible. Por- 
tions of the frontals, the nasals, the prefrontals, the parietals 
and the supratemporals can be identified. Their arrangement 
is shown in figure 3, plate 7. There is a decided posterior 
table to the skull, with a truncate posterior border. The tym- 
2—Univ. Sci. Bull., Vol. VI, No. 2. 
