112 
phologie und Physiologie“ at Munich. He established the order 
Proganosauria, based on Stereosternum Cops, which he con- 
sidered as ancestral to all Amniota. 
The Sauromammalia were regarded as the ancestors of both 
Theromora and Mammalia. This view has been considered by 
many as the most probable one. We shall see that it is not correct. 
It will be shown, that the order Theromora has no existence. The 
Pelycosauria can not be brought together with the Anom- 
odontia, since they have both the upper and lower tem- 
poral arches, like the Rhynchocephalia. 
The material on which this result is based was collected during 
the spring of this year, by the junior author while in charge of the 
fieldexpedition of the Department of Palaeontology of the University of 
Chicago. The locality is in Seymour County, near Bellah, in the breaks 
of the Little Wichita River, belonging to the Wichita Division of the 
Permian. 
In this preliminary communication we shall only give a short 
account of the morphology of the skull, of a well-preserved specimen, 
which at present we refer to Dimetrodon incisivus Cope. We 
retain for the final paper a revision of the genera of the Pelyco- 
sauria, which many points brought out in this and other specimens 
seem to make necessary. 
This specimen consists of the skull, nearly complete, with the 
bones disarticulated, and very little, if at all distorted. The vertebral 
column is known from cervicals, dorsals, and caudals. Of the cervicals, 
the atlas with exception of the neural arches, the axis, the third cer- 
vical, and three others are preserved. There is one, possibly two 
missing. The number of dorsals found is sixteen; eleven of which 
are well preserved. Five or six retain the enormous spines almost 
complete. In the 9th the spine is entire. Its length is 0,863 m. The 
vertical diameter of the centrum is 0,033 m, the horizontal 0,026 m. 
The spines of other vertebrae equal or even surpass this one. The 
sacrals are not preserved, but other specimens show that there were only 
two vertebrae in the sacrum, and these were free from each other. The 
sacral ribs, distally expanded horizontally, were united by suture with 
the anterior portion of the centra. Of the caudals, five belong to the 
anterior region and very probably follow the sacrum, or are very close 
to it; 3 of these are in connection. The ribs are long and slender, 
and curved much forwards and downwards. ‘The posterior caudals 
become small and slender, indicating that there were certainly not 
less than thirty caudals, and possibly more. Intercentra are pre- 
