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cusp of the talon, hyd. In Miacis of the lower eocene (6) the 
figures of the internal and crown views of the three molars show how 
the primitive anterior portion (trigonid) of the crown was reduced to 
the level of the posterior portion (talonid) while retaining all of its 
cusps. In the next figure (7) we see the lower molars of the oldest 
monkey or lemur known, Anaptomorphus, which illustrate the 
Fig. 1. Evolution of the Cusps of the Human Lower Molar. 
loss of the antero internal cusp or paraconid, pad, — this is present 
as a rudiment in m! and m? but has disappeared in m3. This 
accounts for the history of all the cusps in the human lower molar. 
Thus in the rich series of mesozoic!) and lower eocene Mammals we 
can observe the actual rise, succession and decline of all the six cusps, 
and do not require any new hypothesis to explain their appearance. 
Dr. Röse supports his fusion hypothesis by a reference to the Multi- 
tuberculates (p. 403); he could hardly have made a more unfortunate 
choice, because between the little pauci- tubercular Microlestes of 
the upper triassic and the multi-tubercular Neoplagiaulax of the 
lower eocene we can follow the successive addition of tubercles with 
ease. I expect soon to demonstrate that the molars of this aberrant 
group were also of tritubercular, i. e. haplodont origin. 
1) See the Memoirs of Owen and Osporn upon the mesozoic 
Mammalia. 
