564 MR. M. F. WOODWARD ON [May 5, 
attained equal importance with the trigon and developed two 
large cusps, an internal entoconid and an external hypoconid. 
This tooth is further specialized in the partial suppression of the 
paraconid, the antero-internal cone of the trigon, while the pro- 
toconid (antero-external) and the metaconid (postero-internal) are 
very large. 
Taking the case of the upper molar first, in both my specimens 
m.1 was fairly advanced, showing indications of four cones, viz., 
the para-, meta-, proto-, and hypo-cones, here mentioned in order 
of size ; the hypo-cone was obviously the last of the four to develop, 
as it is only just recognizable in the younger specimen; in the 
older stage these cones are larger, and the first trace of the meta- 
conule is here apparent. Thus in m.1 we can say for certain that 
the metaconule appears last and the hypocone next to last, but 
the trigon was too advanced in my specimens to determine the 
developmental order of its cones. But where m.1 fails us m.2 
comes to our rescue: in the younger stage two cones only were 
apparent, viz., the two external ones, the para- and metacones, 
and of these the former was much the largest and must obviously 
have developed first ; immediately internal to this was a low shelf, 
in the position of the future protocone, but at present no cone was 
recognizable. In the older stage of this tooth the protocone has 
appeared in this position, and a faint indication of the heel is 
visible. We may thus state with certainty that the order of cusp 
ontogeny is as follows :— 
1. Paracone 
2. Metacone + Trigon. 
3. Protocone 
4. Hypocone. 
5. Metaconule. 
In the lower jaw, as in the upper, the first molar was too far 
advanced, all five cones being recognizable, but nevertheless 
differing greatly in their relative sizes ; the following is their order 
according to size, viz., proto-, meta-, ento-, hypo-, and paraconid, 
the last being only just recognizable. An examination of m.2 
throws more light on the subject, for here only three cones are 
developed as yet, viz., the proto-, meta-, and entoconid, a slight 
antero-internal extension of the tooth-germ indicating the position 
of the future paraconid, while a similar but larger postero-external 
platform marks the hypoconid. The protoconid is larger than the 
metaconid at this stage, and the metaconid than the entoconid, 
the probable order of development being :— 
1. Protoconid. 
2. Metaconid. 
3. Entoconid. 
4. Hypoconid. 
5. Paraconid. 
The ordinal position of the paraconid in the ontogeny may 
