Further studies on cynodont endocasts (Reptilia--Therapsida).

Endocranial casts of the cynodonts Andescynodon mendozensis, Probelesoden sp., Massetognathus pascualis and M. teruggii are studied qualitatively and quantitatively. The former two show large and flat olfactory bulbs, little or no representation of the olfactory peduncles, long and narrow cerebral region and laterally protruding flocculus at the cerebellar region, specially developed in Andescynodon. The specimens of Massetognathus show long, narrow and elevated olfactory bulbs, well represented olfactory peduncles, wide cerebral region (specially in M. pascuali) and pineal foramen (specially developed in M. teruggii). The encephalization quotients are in agreement with previous results on cynodont endocasts. One specimen of Andescynodon shows a range of 0.097-0.15 and Massetognathus pascuali 0.12-0.18.