The following measurements will show the differences in the proportions 

 between the recent and the Mound specimens. 



Breadth. Length. 



Average dimensions of ( Recent, 41.8 67.0 



ten largest specimens, ( Mound, 40.7 63.1 



a -i n i i inn l m • ( Recent was 63. 



Assuming length to be 100, breadth in j jj;, 1UU(: i gg 



„. . ,, , , ■ (Recent, 47. 75. 



Dimensions of largest specimen, M * 45 _ 6? _ g 



Purpura luteostoma Chemnitz. 



The specimens referred to of this species from the Omori Mounds are so much 

 larger than any Purpura found today in the Bay of Yedo that it is quite difficult 

 to determine their affinities. At present, the species described under the names 

 of luteostoma and clavigera can be pretty easily determined. In the Omori days 

 the forms were not so well defined. The nearest resemblance to the Omori 

 Purpura is the Purpura luteostoma from the west coast of Japan at Funagawa. 

 Purpura luteostoma, from Tenosima resembles somewhat P. Bronui Duuker as 

 it occurs at Kishiu, while the P. clavigera Küster from Kishiu resembles the 

 variety described by Reeve under the name of P. tumulosa. 



TVe searched in vain for an example of Purpura along the Omori shores. 



The specimens from Yenosima are so small as to be worthless for comparison. 



It is easy to believe that not long ago the various species of Purpura were once 

 varieties of a single species, and that P. Bronui, luteostoma, clavigera, tumulosa 

 and many others are modifications of a single form. Indeed I can recall as 

 great a variation among examples of Purpura, lapillus along the eastern coast 

 of the United States as one sees among these so called species. 



Lischke mentions the length of his largest specimen from Hakodate as 40 

 mm. The largest specimen from Omori measures 53 mm. 



The following are the dimensions of the Omori specimens in comparison with 

 those of Hakodate. 



Breadth. Length. 



10 largest specimens from Omori Mounds, 27.8 47.4 



„ Hakodate, 23.9 35.4 



. , , , , Inn , ul . ( Omori shell is 58. 



Assuming length to be 100, breadth in \ Rakod ^ g ? _ 



