TUSKS OF THE FOSSIL WALRUS. 115 



and of Du Bus's account of Alachtlierium (1887), is : — that there 

 is no evidence for the association of the tusks of Trichecfius (Tri- 

 cliecodon) Huxleyi o£ Suffolk with any one set of the bones of "Walrus 

 discovered at Antwerp rather than with any other ; and inas- 

 much as the tusks which we now possess furnish as sound a basis 

 for generic and specific characterization as do detached and frag- 

 mentary bones of the general skeleton, the title Tricheclius Hux- 

 leyi should hold its place. Whilst further, if the generic term 

 " TrioJiecodon " is to be used at all, it is applicable, not to bones 

 which give no specific information relative to the teeth, but to the 

 teeth themselves in the sense in which Prof. Lankester made use 

 of it fifteen years ago at Prof, van Beneden's suggestion. 



Having disposed of the question of nomenclature, Prof. Lankester 

 proceeds to describe the fine set of large tusks of Trichechus 

 (TricJiecodon) Huxleyi from the Suffolk Crag, which are depo- 

 sited in the Ipswich Museum. These he compares with those of 

 the recent form of Walrus (TricJiechus rosmarus) in the College 

 of Surgeons Museum ; and he draws certain conclusions there- 

 from as to absolute size, sectional diameter, curvature, fluting, 

 and attrition of tusks at different ages and in the two sexes. He 

 finds that in the recent and fossil canines of the Walrus there is 

 a precisely parallel variation. He recognizes four kinds of differ- 

 ences of form resultant from age and sex : — 1. Small tusks, almost 

 straight, with unworn points and large pulp-cavity : these beloug 

 to young individuals. 2. Pull-sized tusks, more slender and 

 curved and w T ith less pronounced fluting and ridges than in no. 3 : 

 these appear to belong to females. 3. Pull-sized tusks not longer 

 than the last, but less curved and more massive, and having a 

 greater transverse diameter and a more marked grooving and 

 ridging of the flattened sides of the tusk. 4. Short massive tusks 

 with the pulp-cavity filled by osteodentine : these are worn- 

 down tusks of old individuals, and exhibit a difference in girth 

 accordingly as they have belonged to male or female. 



"With regard to curvature, maximum size, and fluting of the 

 Crag Walrus as compared with the living form, while there is a 

 certain agreement between them, the former (T. Huxleyi) are dis- 

 tinguished by their greater size and curvature, their relative lateral 

 compression (the recent tusks of I 7 , rosmarus havinga more circular 

 contour), and a some what deeper and more constant longitudinal 

 fluting. 



In an appendix the author reasons concerning the conditions of 



