119 
The Mammals have a single temporal (zygomatic) arch; the po- 
‘terior nares are placed far behind, and are roofed over by the 
maxillary-and pterygoid plates; the quadrate is completely co-ossified 
with the squamosal and quadratojugal; the occipital condyle is double, 
the entepicondylar foramen is present in all the generalized forms. 
The ancestors of Mammals must show the same condition. 
SEELEY‘) has combined a number of Permo-triassic Reptilia from 
South-Africa into an order, which he calls Gomphodontia. These 
Reptiles are: Tritylodon Owen (always so far considered a Mam- 
mal), Diademodon SEELE, Gomphognathus SeEELEY, Micro- 
gomphodon SEELEY, and Trirachodon SEELEY. 
In Gomphognathus we have a double oceipital condyle; the 
posterior nares are placed far behind and are roofed over by the 
maxillary and pterygoid plates, and there is an entepicondylar fo- 
ramen. The quadrate seems to be of the reduced form; a condition 
we see also in the closely related Cynognathus?). 
These forms look very much like Mammals and could possibly be 
ancestral to them. We must suppose that the condition of the palate 
we see in the Mammalia and Gomphodontia, has been deve- 
loped from a type we find among the Rhynchocephalia. The 
Crocodilia, where we have a similar palate as in Mammals, show 
us, how such a type of palate was developed from the Rhyncho- 
cephalia, through the Belodonts and the Teleosaurs. It is possible, 
that the Gomphodontia originated from the Proganosauria. 
The question to be solved now is: What is the single temporal arch 
in the Gomphodonta and Mammalia? There are two possibi- 
lities; it represents either both the upper and lower arches united, 
or the lower one alone, the upper one being reduced. 
SEELEY *), in his paper on the Cynodontia, gives a lateral 
view of the skull of Cynognathus crateronotus. There is a 
large supratemporal fossa, but besides, there is a small vacuity, be- 
1) H. G. Surrey, Researches on the Structure, Organization, and 
Classification of the Fossil Reptilia. Part IX, Section 4. On the 
Gomphodontia. Philos. Trans. R. Soc. London, Vol. 186 (1895) B. 
p. 1—57, Pl. I. II. (Published 28th of March 1895.) 
2) H. G. Serrer, Researches on the Structure, Organization, and 
Classification of the Fossil Reptilia. Part 1X, Section 5. On the Skeleton 
in the Cynodontia from the Karoo Rocks. Philos. Trans. Roy. Soe. 
London, Vol. 186 (1895) B. p. 59—148 (Fig. 8 p. 81). (Published 28th 
March 1895.) 
3) SEELEY, H. G. Philos, Trans, Roy. Soc. London, Vol. 186, 1895, 
m: 32,.Fig. 5. 
