214 PKOF. E. EAY LANKESTEE ON WALRUS-TUSKS 



the present occasion to discuss the value of the characters by which Prof, Van Beneden 

 considers himself justified in founding two genera — the one, Alachtherium, having been 

 previously proposed without any definition by the Viconite du Bus (Bulletin de l'Acad. 

 Boy. Belg. 1867, p. 562), whilst the other had been adopted by me for the Walrus-like 

 tusks in 1865. But I must point out that though Prof. Van Beneden figures a number 

 of bones of his Walruses, he is unable to bring any evidence with regard to the tusks 

 beyond that afforded by the small fragment which I saw in 1861. There is actually 

 no evidence whatever that the particular bones referred by Prof. Van Beneden to the 

 genus Trichecodon have any thing to do with the fragment of a tusk in his possession ; 

 certainly there is nothing to show that these bones have any special relationship to the 

 Suffolk tusks to which iu 1865 I applied the generic term Trichecodon. As applied to 

 bones, ''Trichecodon," is an obvious misnomer; and there appears to be no reason 

 whatever for assigning that name to the bones to which it has been assigned by 

 Prof. Van Beneden, rather than to the bones to which he has applied Du Bus's generic 

 term "Alachtherium." The genus Alachtherium was indicated by Du Bus in 1867. 

 The first published reference to Trichecodon by Prof. Van Beneden is in 1871 (Bulletin 

 de l'Acad. Boy. Belg. 2nd ser. t. xxxii. p. 164), where he cites both bones and the 

 solitary fragment of a tusk (which is all as yet recorded from Belgium), and applies to 

 these remains the title Trichecodon Koninckii. 



It must be obvious that, in default of specimens showing both bones and tusks in 

 juxtaposition, it is perfectly hopeless to attempt to identify either Prof. Van Beneden's 

 own fragment of a tusk or the Suffolk specimens with those bones which he calls Alach- 

 therium on the one hand, or with those which he calls Trichecodon on the other. At the 

 same time, should there really be only one Walrus-like animal proper to this period, 

 neither Alachtherium Cretsii of Du Bus (1S67), nor Trichecodon Koninckii of Van 

 Beueden (1S71), has priority as its title, but Trichecodon Huxleyi, mini (1865). Further, 

 if it should appear (as I am inclined to think it will) that there is insufficient ground 

 for the generic subdivisions indicated by the terms Alachtherium and Trichecodon, 

 the species Trichecus Huxleyi will yet have precedence, and any bones which may be 

 referred to the same species as that which carried the tusks which are so well represented 

 in Suffolk will have to bear the title T. Huxleyi. 



This being the case, the following passage extracted from Prof. Van Beneden's 

 memoir appears to me to be open to correction on one or two important points. He 

 says, p. 53, under the heading Alachtherium Cretsii, " On a trouve en Angleterre 

 d'enormes dents dans le crag que Ton avait meme attributes au Dinotherium et qui pro- 

 viennent probablement de l'animal qui nous occupe. Une dent canine est figured dans 



les Proceedings de laSociete Geologique de Londres de 1865, pi. xi En 1S65, 



M. Ray Lankester fait mention de ces dents a la Societe Geologique de Londres ; mais 

 [A] comme on ne connaissait que le genre que j'avais £tabli sous le nom de Trichecodon, 

 il avait cru devoir les attribuer a une espece nouvelle, qu'il d6dia a M. Huxley, Triche- 

 codon Huxleyi Mais comme nous avons deux genres fossiles differents de 



Trichecides, V Alachtherium et le Trichecodon, [B] auquel des deux ces grandes defenses 

 appartiennent-elles ? [CJ Nous pensons que e'est a Y Alachtherium, qui s'eloigne plus 



