MAEGINELLA. 85 



G. 4211. A large series of specimens showing stages of growth. 



Presented hij John Dennant, £sq. 



G. 9340. Four examples of the adult. Purchased. 



Marginella propinqua, Tate. 



1878. Margiiiella propinqua, Tate, Trans. Phil. Soc. Adelaide, 1877-8, 



p. 94. 

 1832. Marginella propinqua, Kirk, Trans. N.Z. Inst. vol. xiv. p. 409. 

 1889. Marginella propinqua, Dennant, Trans. Roy. Soq. South Aust. 



vol. xi. p. 43. 

 189-5. Marginella propinqua, Tate and Dennant, id. vol. xix. pt. 1, p. 111. 



This species differs from M. winteri in being broader, and in 

 having a much shorter spire. In studying the stages of growth, 

 which are illustrated by an excellent series of specimens in the 

 Museum, the following particulars concerning the columellar 

 plications may be noted. In the neanic stage of some individuals 

 four equal-sized, well-developed plaits occur, whilst in others the 

 two posterior plaits are much smaller than the anterior. As the 

 ephebic stage is attained a fifth, posterior plication appears, which 

 is placed farther within the aperture of the shell, and is very 

 small. In many individuals, however, only four plaits occur, 

 even towards the gerontic stage, and one specimen in the collection 

 possesses three large anterior plaits and one very small posterior. 

 Another point of interest is the development of the crenulations 

 on the outer margin. In the majority of specimens these are 

 found from the neanic stage onwards ; but it is clear from others 

 that crenulations were not developed, even up to the early portion 

 of the ephebic stage, although the thickening of the outer margin 

 took place under both conditions. 



The foregoing observations, in the opinion of the writer, are 

 calculated to shed some light on the systematic value of the colu- 

 mellar plications and the crenulations on the outer margin, in this 

 group. It is customary with authors, dealing with Marginella, 

 to lay especial stress on both these characters, in assigning species 

 to subordinate divisions of the genus. Yet in M. propinqua 

 these features are very unstable, and certainly ought not to 

 rank higher than ontogenetic characters. Some authors might 

 be disposed to create another specific name for the non-creuulate 

 forms; but in carefully examining a series of the shells, it is 



