The Nuclear Pattern O F the Non-tectal Portions

The midbrain of the armadillo has received little consideration from comparative neurologists, although the pretectal nucleus was described by Papez ('32) in his study of the diencephalon of this form. The general development of the nervous system in this mammal had been considered much earlier by Newman and Patterson ('10). Papez called attention to the fact that in many ways the brain of the armadillo (Tatusia novemcincta) resembles that of insectivores and this study, in general, confirms that conclusion, although the armadillo brain shows less evidence of compression than does that of the short-tailed shrew (Blarina brevicauda). The material on which this account is based consists of a complete series of sections transversely-cut and stained with toluidin blue. The illustrations are in the form of photomicrographs taken at a magnification of 10 for the cross sections and 11 and 3 for the orientation figures.