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cone in the first developed cusp, i. e., the anterior outer cusp above 
and below — (this is in accordance (!) with Winge’s theory in 
which paracone and protoconid, metacone and hypoconid respectively 
are homologised) — this cusp may be called the Primary cone. 
Around this a cingulum early arises (both palæontologically and 
embryologically), from which various cusps appear, the most constant 
being the Anterior c i ngul um-cusp and Poste rior cingu¬ 
lum-cusp. On the posterior slope of the primary cone the Se- 
condary cone arises, linally a Centro-internal cingulum- 
cusp appears on the inner cingulum. These cusps can not be 
fully identified with the nomenclature of Osborn, the names of the 
latter often being applied to different cusps on various teeth; but 
approximately they correspond with one another in the following 
manner: 
Both jaws. (Tims) 
Upper jaw 
Lower jaw (Osborn) 
Primary cone 
Paracone 
Protoconid 
Anterior cingulum-cusp 
Protocone (partly) 
Paraconid (partly) 
Posterior cingulum-cusp 
Metacone (partly) 
Hypoconid (hind part) 
Centro-intern. cing.-cusp 
Premolars: wanting 
Molars: Heel (partly) 
Premolars: wanting 
Molars: Metaconid 
Secondary cone 
Metacone (partly) 
Hypoconid (partly) 
This Cingulum-cusp Theory is better supported, both palæontologi¬ 
cally and embryologically, than are either the Tritubercular or the 
Multitubercular Theories. The primary reptilian cone is always 
present; and it is usually easy to find the homology of every 
tooth-cusp (perhaps except those of the Multituberculata). 
In Woodward’s examination of the tooth-development of 
the Insectivora (1896), the problem of the tritubercular type is 
also discussed. In his opinion the foremost of the three original 
triconodont cusps has disappeared; the main cone is that which is 
now called paracone, the hindmost is the metacone, the falsely 
