( II ) 



tlierium, on the olhcr hand, shows a long coronoid process, which 

 has a backward and slightly inward direction, and which on account 

 of t lie nn-f'ree situation of' the articulation of the cranial fragment, 

 must inevitably come in collision with the. squamosum ; hence the 

 two bony pieces cannot possibly belong together. 



So we may conclude that the skull described as Alachtherium 

 does not belong to this species. No more can it belong to Triche- 

 codon, since this genus must disappear from literature. So it must 

 be regarded as undetermined. 



Finally the "Musée d'Histoire naturelle" at Brussels possesses still 

 another Trichechid skull, floated ashore near lleyst and considered 

 to be diluvial. It is the cranium of a very old male: the sutures 

 have all disappeared and the tusks are almost entirely used up. 

 The preservation is exactly as that of the Zealand fossil : the bones 

 have turned brown and the teeth entirely black; the skull is verj 

 heavy and perhaps has become partly siliceous. Besides its shortness 

 and a strong development of the alveoles of the tusks, the fossil 

 shows no differences with the walrus: these two characteristics, 

 however, give it a very square appearance. But these small diffe- 

 rences give us no right to regard the skull as a new species: it 

 seems to be an ordinary Trichechiis rosmarus. After having dealt 

 with the known skulls, we must assign a place in the system to 

 the Zealand fossil and to the Antwerp hind skull. They belong to 

 different species. The resemblance of the tusks of Trichechus Huxleyi 

 with those of the Zealand cranium was already pointed out. The 

 curvatures of the tusks of Trichechus Huxleyi, drawn by Ray Lan- 

 kester, are: 



21, 27, 30, 38, > 50, > 50 cms. 



Hence they agree much better with the Zealand tusks than with 

 those of the walrus. Also the cross-sections of the tusks showed 

 analogies and so we may safely class (lie Zealand skull under 

 Trichechus Huxleyi. . 



If we ask what age must be attributed to the skull from the 

 Scheldt, we must bear in mind that the good state of preservation 

 precludes a long transport. Hence the skull must have been dislodged 

 out of the bottom of the river. What sort of soil do we find there? 

 Formerly already Dr. de Man has described remains of diluvial 

 terrestrial mammals (35), which were also fished from the Scheldt 

 and partly even very near the spot where also the Trichechus was 

 found (36). Now it is very improbable that the Trichechus and the 

 terrestrial mammals come from the same layer, since both are well 

 preserved. In the year 1879 Dr. Seei.iieim published some profiles 



