On the Teeth of certain Ruminants. By M. V. Pietkiewicz. 291 
actually copied as they appeared in setw in the field of view of the 
microscope, some processes and other bodies being omitted for 
the sake of clearness, and the peripheral members of the group 
sometimes brought nearer to the centre to save space. Numerous 
other preparations were made at all stages of inflammation, com- 
mencing with five hours, when little or no change was observable, 
up to five and seven days, when, in the case of inflammation 
induced by nitrate of silver, the effects had passed off, leaving no 
recognizable traces.—Proceedings of the Royal Society, No. 177.* 
VI.—Goodsir’s Arguments on the Development of the Teeth of 
certain Ruminants. By M. Y. Prerximewicz. 
In a communication made to the British Association in 1839 
Goodsir announced that he had discovered in the jaw of the calf 
and sheep the germs of incisor and canine teeth, and even of a 
molar, intermediate between an abortive canine and the ordinary 
molars which exist in these animals. Geoffroy Saint-Hilaire had 
already described abortive dental germs in the lower jaw of the 
baleen whale (Balena mysticetus). Naturalists, partisans of the 
theory of Lamarck, and of Evolution, Darwin particularly, seized 
hold of this idea; and thus associating the discoveries of compara- 
tive anatomy and paleontology, this embryological discovery per- 
mitted the association of groups of animals which had before been 
separated. 
Everyone knows the difference which exists between the dental 
formula of ordinary ruminants, as the ox and sheep, whose formula 
is 1} C$ M &, and the formula of the omnivorous pachyderms, the 
hippopotamus and the wild boar (le Sanglier),I13C1Mz. But 
all authors have found the presence of superior canines in two or 
three genera of ruminants, the deer and the goat, which have a 
formula of I$ C+ M €, and the existence of a pair of very distinct 
upper incisors in the camel (chameau) and lama (Jamas), giving the 
formula 1} C} M&. According to M. Paul Gervais these latter 
had even two pairs of upper incisors, one of which disappeared in 
the adult, but was present in young animals, so that they would 
have this formula 1? C+ M&; this author does not doubt either ~ 
that if the animal was examined at a younger age stili, one would 
find a third pair of incisors in them, and thus that their dental 
formula would be related to that of pachyderms minus one molar: 
I3C{}Mé&. Then, on the other side, the study of fossil species 
has shown that the Dinotheriwms and the Amphitragalus, con- 
sidered as ruminants of the group of Chevrotins, have seven molars 
* Professor Huxley has kindly given permission for its reproduction here.— 
Ep. ‘M.M.J.’ 
