456 CENSUS OF THE MARINE MOLLUSCA OF TASMANIA, 



under the description of the species, " labio, plica unica incon- 

 spicua." 



The genus is composed of a few living and rare species, and by 

 extinct species in the Eocene of Australia, Miocene and Pliocene 

 of France. 



M. Flindersi, Pritchard k GatlifF, is certainly the same as 

 M. cilba^ and M. Brazieri, E. A. Smith, is probably synonymic; 

 the species occurs in South Australia, Victoria, Tasmania and 

 New South Wales If M. volva, G. B. Sowerby, ©f S. Africa, is 

 identical, then J£ alha antedates it. 



COLUBRARIA BbDNALLI. 



The white or grey colour of the test is varied, as seen in good 

 specimens, by two rows of yellowish spots on the spire whorls, 

 one at the posterior suture and the other at the anterior third; 

 on the body-whorl there are in addition a few spots around the 

 base of the snout. 



Semicassis pyrum, Lamarck (Cassis). 



Under this name we include ^S. paucirugis and S. nivea; all 

 the forms occur in Tasmania. 



S. pyrum typica has subtabulate whorls, S. pyrum paiiciriigis 

 has tabulate whorls, and >S'. pyrum nivea has convex whorls; but 

 they are connected together in respect of marginal outline by 

 intermediate examples. 



The species exhibits great variation in the number and strength 

 of the spiral ornament. Also as regards the development of 

 tubercles; thus the series of tubercles on the periphery occupies 

 usually from one to one and three-fourths turns, rarely two and 

 one-half, sometimes only half a turn restricted to the posterior half 

 of the body- whorl; in others the series is interrupted ; a second row 

 is occasionally developed on the anterior half or two-thirds of the 

 body-whorl. 



The development of the columellar ridges and of tubercles on 

 the outer lip increases with age ; though in the majority of 

 examples the margin of the outer lip is smooth; the denticulation 

 of the lip, an inconstant character, cannot therefore be regarded 



