POSITION OF FOSSARINA — KESTEVEN. 819 



A second species, F. brazieri,^^ was described by Angas from 

 Sydney Harbour ; the differences between the two are slight, and 

 all the intermediate forms are obtainable ; the name must there- 

 fore be regarded as a synonym of F. patula, though it may be 

 retained by pedants as a cabinet variety. 



Part II. — Fossarina varia. 



Button's mistake in making the genus Minos was practically 

 unavoidable, because his F". varia answered in every way to the 

 description of Fossarina; it has a subspiral operculum, and the 

 dentition shows it to be related to Littorina. His tenative refer- 

 ence of the species to Risella,^- seems to show that he was well 

 aware of these facts, consequently he had no reason to doubt the 

 correctness of Adams and Angas' description; but in these points, 

 as we have seen, it differs widely from that genus. It, therefore, 

 devolves on me to make a genus for the reception of the species. 



Fig. 29. 



RiSELLOPSis, gen. nov. 



A genus closely allied to Risella}'^ 



Shell. — Comparatively small; stomatiform or depressed trochoid, 

 perforate, rather solid, spirally ribbed or carinated transversely, 

 growth striate ; aperture oval (subject to modifications caused by 

 sculpture), oblique, interior porcellaneous, outer lip sinuated 

 according to sculpture, columella short, curved; operculum corneus 

 subspiral (Fig. 29). 



H Angas-Proc. Zool. Soc, 1871, p. 18, pi. i., f. 24. 

 12 Hutton— Journ. de Conch., 1878, p. 27. 

 15 Hence the name. 



