032 Dr. W. D. Matthew—Relationship of the Sparassodonta. 
characters of the group, embracing twenty or thirty more or less 
independent points of structure, and including most of the important 
osteological peculiarities of modern Marsupials. There are, however, 
certain points of difference. 
1. Sinclair’s material did not enable him to demonstrate any more 
extensive replacement of the premolars than prevails among modern 
Marsupials, viz. p.4 only. Ameghino states that in Borhyena the 
canine and in Cladosictis the canine and second premolar are also 
preceded by milk-teeth. 
2. Palatine vacuities, characteristic of most Marsupials, as well 
as some placental mammals, are lacking in this group. 
8. There, are no indications of marsupial bones. This does not 
necessarily mean that they were absent; they may have been small 
and without distinct articular facets, and not preserved in the fossil 
skeleton. They are vestigial in Thylacinus. 
4, Enamel structure as in Placental Carnivora. This is known only 
in one genus, Borhyena, the largest and most specialized of the group. 
Mr. Tomes’ paper was not published at the time Dr. Sinclair’s 
monograph was written, so that this important point was unknown 
to him. 
On the other hand, we have— 
1. Dental formula typically marsupial, with three premolars and 
four true molars, as opposed to the placental formula with four 
premolars and three true molars. 
2. The characters of the basicranial region agree with Marsupials, 
in some respects also with Insectivores, and differ from Creodonts and 
modern Carnivores. ; 
3. The malar bar is extended posteriorly to take part in the pre- 
glenoid process. 
4. The posterior border of the palate is perforated by a large 
foramen on either side of the posterior nares. 
5. Post-zygomatic and sub-squamosal foramina present. 
6. Transverse process of seventh cervical vertebra perforated by 
vertebral artery. 
7. The arrangement of carpals and tarsals is in fairly close agree- 
ment with Carnivorous Marsupials, and decidedly different from the 
type common to Creodonts and the less specialized Carnivora. In 
particular, the small lunar and large magnum, the peculiar type 
of astragalus, etc., agree with Marsupials generally and differ from 
Placentals generally, the agreement and difference being very marked 
when comparison is confined to Carnivorous Marsupials and Placentals. 
Various other characters are listed by Dr. Sinclair, but the above 
appear to be the most essential. In the writer's opimion any one 
ot these outweighs in importance all of the characters except the last, 
in which the Sparassodonts differ from Marsupials. The enamel 
structure is doubtless a character of high importance if constant 
‘throughout the group, but even if it proves to be so it admits of 
an explanation which would bring it in accord with the marsupial 
relationships of the group. 
_ Dr. Lydekker is not convinced by the evidence adduced by 
Sinclair. He regards the Sparassodonts as descended from Creodonts. 
