123 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



G. 4244. An example of the adult stage. 



Presented hij John Dennant, Esq. 



Subgenus CANCILLA, Swainson. 

 [Malacology, 1840, p. 320.] 



Spire elevated ; ■whorls ornamented by spiral ridges ; outer 

 margin of the aperture thin. 



The heterogeneous forms usually included in this subgenus 

 sufficiently attest the absurdity of utilizing ornament of the whorls 

 for systematic purposes — at least, so far as chief subdivisions are 

 concerned. Cancilla may, however, be provisionally retained in 

 its present state, until the Miteid^ as a whole are classified 

 according to more modern methods. 



Type. — Mitra sulcata, Swainson, 



Mitra (Cancilla) atractoid.es, Tate. 



1889. Mitra [Cancilla) atracfoides, Tate, Trans. Roj-. Soc. South Aust. 



vol. xi. pp. 135, 139, pi. iv. fig. 11. 

 1893. Mitra atractoides, Tate and Dennant, id. vol. xvii. pt. 1, p. 220. 



The protoconch (Plate V. Pigs. 2a-b) in this species is large, 

 obtuse, and composed of four turns, the first three of which are 

 implanted obliquely, in the majority of individuals; its suture 

 is somewhat canaliculate, the surface of the shell being smooth 

 and polished, but the fourth turn is spirally lineate, the lineations 

 being in strict continuity with those, more plainly marked, on 

 the whorls in the brephic stage. 



The shell as a whole is somewhat fusiform, with a rather 

 elevated spire of five convex whorls ; spiral ridges conspicuous 

 and regular, crossed by sinuous growth-lines. Aperture half 

 the length of the shell, narrow, slightly dilated anteriorly ; 

 columella with four prominent plications in the ephebic stage ; 

 and sometimes with five in the gerontic, owing to a very small 

 one being developed anteriorly. 



The fusiform shape of the shell, the subcancellate aspect of 

 the external ornament, and the size and general character of the 

 protoconch, are very distinctive. 



