FEOM THE RED CRAG OF SUFFOLK. 217 



curved, and with evidence of a large conical basal pulp-eavity. The specimen drawn in 

 fig. 7 is a somewhat large example referable to this group. 



As parallel to the second group of recent Walrus-tusks, I am able to cite the beautiful 

 example drawn in Plate XXII. fig. 2, besides numerous fragments. The relatively large 

 curvature, the relatively slender proportions, the great lateral compression, and the 

 feebly marked surface-fluting, as compared with tusks referable to the next group, are 

 unmistakable characters in which this set of the fossil tusks agree with those known to 

 belong to females of the living Trichecus. 



The largest, most massive, longest, most strongly ridged specimens which are found 

 in Suffolk, agree with the similarly characterized male tusks of living Walrus in 

 being also less curved than are those of the female. A fine example of the male tusk 

 from Suffolk is drawn in Plate XXII. fig. 1. The base of a still larger specimen, indi- 

 cating the largest Walrus-tusk, recent or fossil, which I have encountered *, is drawn in 

 fig. 3. In fig. 4 is drawn the point of a tusk, probably that of a male (on account of its 

 strong fluting), although exhibiting much greater lateral compression than is usual in 

 the tusks of the living male Walrus. Such flattened tusk-points are not uncommon in 

 Suffolk, and possibly indicate a Walrus-like animal distinct from that with less-com- 

 pressed tusks. 



Lastly, we have from Suffolk specimens corresponding exactly to the 4th group of 

 tusks noted above as distinguishable in the collection of the Royal College of Surgeons. 

 One of these is drawn in fig. 5, and another in fig. G. They are distinguished by the 

 wide base, filled with a solid osteodentinal core and a (comparatively) very rapid tapering 

 of the tooth, which is relatively short and stumplike. These are undoubtedly old worn- 

 down tusks, and may be either those of males or of females. 



Observations on the Curvature and Maximum She of recent and fossil Walrus-tusks, and 

 on the Fluting and Proportions as exhibited by Transverse Sections. 



I obtained a number of outlines of the transverse sections of Walrus-tusks preserved 

 in the museum of the Royal College of Surgeons by means of modelling wax applied as 

 a ring to the tusk ; the ring was removed after pressure, and a pencil was drawn around 

 the inside of the ring when held on a piece of paper. These transverse sections may be 

 compared with those of the fossil tusks, and give the best means of estimating the differ- 

 ences which the two sets of tusks (the living and the fossil) present in respect of fluting 

 and transverse proportions. 



It is to be noted that the fluting of the recent tusks is very varied in the different 

 specimens studied. The tusks are always oval in section, being somewhat compressed 

 laterally. One may find a single groove only on each side of the tusk ; or there may be 

 two grooves on the outside of the tusk and none on the inside, or there may be merely 

 the faintest indication of grooving (see figs. S to 14). 



The same variation obtains in the fossil tusks from Suffolk ; some are more, some less 

 deeply fluted. But, as compared with the tusks of living Trichecus, the tusks of Tri- 



* A specimen of the tusk of T. rosmarus recently acquired by the Royal College of Surgeons' Museum, to which 

 my attention has been called by Frof. Flower, is fully as large as this. 



