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Crossea labiata (Tenison- Woods). 

 The fossil shells, originally referred to the living species 

 described by Rev. J. E. Tenison- Woods, were again submitted 

 by me to a most careful comparison with a fine collection of 

 living forms. As the result of this examination, I still find 

 that, although the fossil representatives are decidedly larger 

 than the living ones, there are no characteristic differences 

 between them, so far as the tests are concerned, if we except 

 the fact that in the living form the varix bordering the 

 aperture is generally sharper and more decidedly reflexed. 

 This character is constant in all the individuals — nine or ten 

 -;-examined by me. In the fossil representatives the striae 

 upon the varix are almost obsolete, and, consequently, the 

 latter has not that appearance which Mr. Woods describes as 

 " fringe-like." It must be confessed, therefore, that it would 

 be difficult to separate the hving from the fossil so far as 

 absolute differences are concerned. Still, so far as the 

 trifling differences go, I must admit that they are sufficiently 

 constant to enable a careful classifier to recognise the living 

 from among the fossil representatives with a considerable 

 degree of confidence, and, perhaps, for these reasons, it 

 might be well to recognise the constant differences, slight 

 though they may be, as of specific value. I hesitate myself 

 to decide in such a case, until I learn how far the Table Cape 

 fossil form agrees with the fossil forms discovered in the 

 same horizon in the South Australian and Victorian forma- 

 tions, which have now been so fully investigated by Professor 

 Tate. 



Natica polita. (Tenison- Woods). 

 Curiously enough, of the two representatives — the fossil 

 and living — hitherto known as N. jpolita, the fossil was the 

 first known to science. The living form was discovered 

 almost immediately after the fossil form was described, and 

 was determined by Mr. Woods to be conspecific with the 

 latter. On comparing a large series of living and fossil 

 forms together, however, I find the following differences to 

 be constantly maintained. In the living form the spire is 

 more depressed, and the whorls increase more rapidly in size. 

 In the fossil form the nucleus is invariably smaller than in the 

 living representative, and the number of whorls in mature 

 specimens is 4J. In the living mature form the number of 

 whorls is invariably Sf. The aperture in both does not present 

 any marked difference, if we except the fact that, in the fossil 

 state, the inner margin is almost vertical. In the living 

 form, the same feature is more decidedly angled relative to a 

 central line drawn through the nucleus. If anything the 



