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single tooth, so that it can be functionally equal to several 
teeth. The most primitive teeth as to form and number are the 
haplodont oonical teeth of Cetacea and Edentata, although both of 
these types are somewhat specialised, the former having acquired 
fangs, the latter having lost their enamel; but as to form they are 
more primitive than those of the Triassie and Jurassic mammals. 
— Among the rodents with ever-growing teeth we find a more 
complicated tooth-form, the enamel of which forms deep vertical 
folds along the sides of the tooth (“Lamellenzahn”). This tooth is 
in the lower jaw often formed like a W. It is conuected with the 
conical tooth by an intermediate form (“Furchenzahn”) which is 
seen in a sligtly aberrant shape in Orycteropus, Glyptodon etc. 
From the ever-growing lamellar tooth all the fauged foims aie 
derived; the W-pattern is ofton conspicuous and the selenodont 
teeth with their deep enamel-folds are not difficult to denve from 
the lamellar teeth; from these folded teeth the bunodont type is 
derived (through forms like Phacochoerus), the folds bemg more 
shallow and filled up with enamel. Thus the most different tootli- 
forrns are referred to ono primitive type which in its turn can be 
traced through the whole series of Vertebrata. 
In the same year that Baume published his cunous theones, 
H. Winge published a short paper entitled “Om Pattedyrenes 
Tandskifte, især med Hensyn til Tændernes Former”. The first 5 
pages contain his views on the development of the tooth-forms 
which for elearness and simplicity greatly exceed any other former 
or later theory; but being written in Danish it is not vet geneiallj 
known nor fully appreciated. ') According to him, in the lower 
vertebrates the teeth are only used for seizing theii piey, the 
lower jaw is moved up and down by the muse. temporalts and 
pterygoideus ; but the mammals masticate their food, their teeth 
being slightly moved from side to side; the mandible is fixed 
x ) A short summary ot this theory has been given in Max We 
»Die Såugetiere« 1904. 
