598 Transactions,—G eology. 
CYCLOSTREMA HELICOIDES, sp. nov. 
Small, depressed. Whorls, four; smooth, spirally striated, flattened 
posteriorly and exteriorly, and with a narrow spiral rib on the anterior part 
of the flattened exterior. Umbilicus wide. Aperture nearly circular. 
Peristome continuous (?). Axis, ‘05. Breadth, +15. 
Locality: White Rock River. 
This species approaches C. biporcata, Adams, but the upper keel is 
obsolete. The only specimen that I have seen has its aperture broken, 
consequently I am not sure whether the peristome is continuous or not. If 
it is not continuous, the shell will belong to the genus Adeorbis, 
CORBULA SULCATA, sp. nov. 
Plate XVI., Fig. 14. 
Trigonal, gibbous, nearly as high as long. Deeply longitudinally 
grooved. Very slightly angulated behind, and rounded in front. Height, 
:82. Length, :85. 
Locality, Mount Harris. 
LEDA SEMITERES, sp. nov. 
Rather compressed, rounded in front, and produced to a blunt point 
behind. Posterior dorsal margin, very slightly concave. Ventral margin, 
regularly rounded. The whole shell regularly and strongly concentrically 
striated. There are between 40 and 50 strie between the umbo and the 
ventral margin. Height, -25. Length, :5. Breadth, -18. 
Locality : Waiho. 
Similar in shape to L. lata, Hinds, from New Guinea and Borneo, but 
easily distinguished by the stronger stris. 
ANOMIA TRIGONOPSIS, sp. nov. 
Sub-trigonal. Lower valve (?). Upper valve, gibbous, solid, rather 
smooth. Museular impressions, three; the upper one the largest, nearly 
round, but flattened below. Middle impression, immediately below the 
upper one, trigonal, the apex angular and pointing downward, the angles of 
the base rounded. Lower impression, placed diagonally below and posterior 
to the middle one ; of the same size and shape as the middle impression, 
but the apex pointing upward. 
Locality: White Rock River. 
