192 



Aperture roundly -oval, channelled at the front ; outer lip 

 smooth within ; columella-reilection concealing the umbilical 

 chink. 



Dimensions — Length, 3 -7 5 ; greatest breadth, 2 ; height of 

 aperture, about 1*0. 



Locality. — Eocene ; glauconitic sands, Adelaide-bore (2 exs.). 



FAMILY SEQUENZIID^. 

 Genus Sequenzia, Jeffreys (1876). 



The genus includes certain small trochiform shells, thinly- 

 nacreous, with an infra-sutural sinus resembling that of some 

 Pleurotomiid^e, a sharp and shallow sinus at the periphery, and a 

 third, more open, at the base ; the columella is more or less 

 twisted, with an anterior tooth-like projection ; the base is either 

 deeply umbilicated or imperforate. Eight species are known 

 from ofi' Pernambuco, and in tropical and subtropical latitudes on 

 both sides of the North Atlantic at depths ranging from 100 to 

 1,500 fathoms. One of the living species occurs in the Upper 

 Miocene of Calabria and in the Middle Pliocene of Sicily. 



The author of the genus placed it near Solarium. Try on in 

 his Manual of Conchology (1883) includes it among Pleurotoma- 

 riidae in the vicinity of Scissivrella. It forms part of Tryon's 

 Monograph of the Family Trichotropidse. Prof. Verrill re- 

 moved it, on anatomical characters, far from its former assigned 

 positions, and made it the type of a distinct family. Watson, 

 Challenger Rep. Gastr. (1886), retains it among the Trochiidae. 

 Dall, Blake Rep. Gastr. (1890), follows Yerrill, and places the 

 family in the neighbourhood of Trichotropidse. 



The presence of the genus in the Older Tertiary deposits of 

 Australia was notified by me in Proc. Roy. Soc. N.S.W., 1888, 

 pp. 243, 249 ; it is represented by a single species which differs 

 from all others by the crenulated margin to the umbilicus and by 

 the bisinuated base of the aperture, as well as by the strongly 

 developed radial ornamentation. 



Sequenzia radialis, si^ec. nov. 



Shell small, thin : broadly conical ; flat and sharply angulated 

 at the base, perspectively umbilicated ; ornamented by radial 

 sigmoidal threads, latticed by spiral ones. 



Whorls seven, those of the spire flat, wdth the peripheral angu- 

 lation exsert, or varying to biangulated, ornamented by equal, 

 equidistant, sigmoid and radial lamelliform threads, and above 

 the peripheral angulation by about four equal equidistant spiral 

 threads, the intersections producing square- to rhomboid- inter- 

 spaces. The radial lamellae are more or less continuous from 



