Fusus. 133 



drawing such a fine distinction, especially if we consider that 

 slight curvature in the columella is due to the merely mechanical 

 requirements of the animal. The protoconchs of the only two 

 specimens in the Museum collectioa are not well enough pre- 

 served for description; but they appear to be of the same "general 

 character as in F. hexagonal^. The shell is narrow, with an 

 elevated spire; whorls convex, angulate, with a median serrate 

 keel and subsidiary spiral lines elevated on the longitudinal 

 ribbings, and crossed by fine growth-lines; aperture angularly 

 ovate; outer margin thin, striate within; columellar border ex- 

 cavated, covered by a thin deposit of callus; anterior canal very 

 long and sinuous. 



Except for the excavated columella, the curved canal, and 

 the longitudinal costae, this shell resembles F. serratm, Deshayes 

 of the Middle Eocene of the Paris Basin. 



Bimemions. — Length 5 1 mm.; breadth 13-5 mm.; length of 

 aperture 1 1 mm. ; length of anterior canal 21 mm. 



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



G. 9435. Examples of the neanic stage. Furchased. 



Fusus senticosus, Tate. 



1888. Fusus senticosus, Tate, Trans. Roy. Soc. South Aust. vol. x p 135 

 pi. vii. fig. 3. ■ V > 



1893. Fhsus senticosus, Tate and Dennant, id. vol. xvii. pt. 1, p. 219. 



_ Shell small, elongate, fusiform, thin; protoconch similar to that 

 m typical forms of the genus, it is much elevated, composed of 

 one and a half smooth turns longitudinally striated towards the 

 anterior; the shell in the brephic stage suddenly develops a strong 

 median carina which rapidly becomes tubular at intervals and 

 continues to increase in size to the body-whorl, imparting an 

 angulose character throughout. In front of this in the brephic 

 stage is developed a minor keel of a similar description, and at 

 a slightly later period of growth a small one makes its appearance 

 posteriorly between the median carina and the suture. Sub- 

 sequently others are gradually interposed until the penultimate 

 whorl in the adult carries five such keels. The mode of growth 

 IS thus of a different character to that of most species of the same 

 group, in which the main features of the ornament are foreshadowed 

 at a very early stage. 



