SVENSKA EXPEDITIONEN TILL MAGELLANSLÄNDERNA. BD. II. N:0 7. 161 



In both cases, whether one or the other theory is right, 

 the ossicles of Mylodontidce and the bony scutes of Dasypo- 

 didce are genetically related as tliey have a similar origin, 

 Imt this relationship dates back to the common ancestors. 1 

 The Mylodonts can therefore not be regarded as a link in the 

 chain of development of Dasypodidce. The ossicles of »Neo- 

 mylodon» seem to be less developed than in the fossil Mylodon. 

 They are thns either remainiug in an earlier stage or be- 

 ginning to be reduced. 



Dr. Ameghino regards this character of having dermal 

 ossicles not as a primitive one, mit as secondarily acquired 

 at a relatively modern period, becanse it is only in the Pam- 

 pas beds and in the. Arancanian Formation and that of Entre- 

 rios such ossicles are met with. >Mais on n'en a pas encore 

 trouve aucnn vestige ni dans les santa cruzien, on les Eden- 

 tes gravigrades sont si abondants, ni dans les formations 

 anterieures.» Bnt it mnst he remembered that already in the 

 Santa Cruz Formation completely armoured Glyptodonts and 

 Dasypodids are to be found. 



The »Reste eines Hautpanzers» in some Odontoceti (Neo- 

 •nicris phoccenoides , Phoccena spinipinnis and communis and 

 Globiocephalus macrorhynchus) which are described by Küken- 

 thal (Anat. Anz. Jahrg. 5 p. 237) are too little known to 

 allow any comparison. 



If we now leave the dermal ossicles of »Neomylodon- 

 which have shown the close affinity between this animal 

 and the true fossil Mylodonts and turn to considering the 

 structure of the hair, we find this stiff and rigid. It is 

 therefore hard to cut and difficult to get good sections, be- 

 canse thin sections are apt to break. It is however easy to 

 observe, and attracts at once the attention that the hair is 

 completely solid so that there cannot be found the slightest 

 trace of a central pith on any section. A transversallv cut 



1 The investigations of Weber and of De Meijebe (Über die Haare der 

 Säugethiere etc.; Morph. Jahrb. Bd. 21, 1894) have shown that Myrmecojjhaga 

 and Tamandua are also provided with scales although only on the tail and 

 feet. The authors mentioned, and Reh (Die Schuppen der Säugethiere, Jenai- 

 sche Zeitachr. f. Naturwiss. Bd. 22 (29) (1894—95) have pointed out the pre- 

 sence of scales in a great nuniber of Mammals. This tends to make it ]iro- 



bablc that the >Ursäuger» — »ein Schuppenkleid» — — — »als etwas 



Fertiges von ihren Vorfahren überkommen». From this point of view the 

 latter of the two theories referred tö above is more acceptable than the former. 

 (Conf. below.) 



11 



