( 2 ) 



Palaeontology. "On fossil Trickechids from Zealand and 



Belgium." By Mr. L. Ritten. Communicated by Prof. C. E. 



A. Wl( II.MANN. 



(Communicated in the meeting of March 30, 1907). 



Last summer a fisherman found opposite the village of Breskens 

 in the West Scheldt a large skull, which Dr. S. Schouten secured 

 for the Geological Institute of Utrecht University. 



The fragment belongs to an old Trichechus, but differs in some 

 respects from the now living Walrus. On closer examination it 

 appeared that the skull must be of the tertiary Trichechus Huxleyi, 

 of which until now only tusks were known, found in the "Red 

 Crag" of Suffolk. These were described by Ray Lankester. Of the 

 skull the description will be given here. 



The plan suggests itself to compare the fragment first with the 

 walrus of recent times and then with the already known fossil 

 Trichechids. 



1. Description of the skull and comparison with the walrus. 



The most conspicuous point about the skull is its remarkably good 

 state of preservation. It has this in common with some remains of 

 diluvial mammals, also found in the river Scheldt. The skull, to be 

 sure, arrived here in several pieces, but the broken edges were absolutely 

 fresh and all parts fit perfectly together. Probably the fossil only broke 

 when it was being dredged. As to completeness the skull leaves nothing 

 to be desired, since only parts of the nasal, maxillary and frontal 

 bones, part of the vomer, the conchae and a few teeth are wanting. 

 The skull was filled with a fine-grained grey clay; the outer wall 

 of the cranium was overgrow with Balanids and Bryozoa. Although 

 the fossil is very heavy, a chemical analysis of a little piece of bone 

 revealed nothing particular. It still contains pretty much organic 

 matter and consists for the rest especially of CaO and P 2 <> 5 , while 

 a small quantity of ferric hydroxide colours the bone dark brown. 



Thai our Trichechus is full-grown, is proved by the fact that all 

 sutures are absent ami by the stront;' development of all ridges. 



As material for comparison we had at our disposal 24 recent skulls 

 and - 2H pairs of tusks. Very unpleasant was the great variability of 

 the recenl walruses. Certain characteristics vary so strongly in 

 differenl individuals thai with the limited material one always remains 

 uncertain whether the analogous characteristic in the fossil lies within 



