Victorian Marine MoUusca. 85 



Cyclostnema microscopica, sp. uov. 

 (PI. XVIII, Figs. 5, 6, 7). 



Shell very minute, of four whorls, rapidly increasing in size, 

 roundetl. The apex is smooth, and is succeeded by lirate whorls, 

 the lirae numbering about five on the penultimate whorl, which 

 increase in number by intercalation to about fifteen at the 

 outer edge of the lij). Deeply umbilicated. Mouth circular, 

 outer lip simple. White, semitranslucent. 



Dimensions of Type. — Diameter, .75 mm. 



Locality. — Shoreham, Western Port (T. Worcester). 



Obs. — An interesting minute form. 



Type in Mr. Gatliff's collection. 



Saxicava subalata, sp. nov. (PI. XIX., Figs. 10, 11, 12). 



Shell white, inflated, somewhat angular ; sub-equal, inaecjui- 

 lateral. Valves slightly gaping anteriorly. Beaks depressed, 

 slightly incurved, produced anteriorly. Dorsal margin 

 straight, somewhat a late posteriorly. Post-dorsal border 

 curved. Ventral margin straight. Post-ventral margin sub- 

 angulate, anterior end rounded. From the lunbo to the pos- 

 terior end runs an oblicpie, well-defined ridge, steep on dorsal 

 side and becoming more rounded as it approaches the ventral 

 margin : the posterior slope thus formed covering about one- 

 third of the entire shell. Ligament external, well developed, 

 and faintly darker than the epidermis. 



Sculpture. — At the umbonal region appear very fine lines of 

 growth, which develop into irregular, somewhat undulating 

 rugae. Besides this concentric sculpture, the whole surface is 

 studded with minute granular excresences developing with age 

 and approaching more the form of tubercles, and which may 

 be plainly seen from the interior of the shell. These are 

 arranged roughly parallel with the rugae. When portions of 

 the shell are examined under a high ])ower (preferably a ninth), 

 these grannies can be focussed from both the inner surface 

 below which is seen the striated vitreous layer, and from be- 

 neath the external layer ; the granules then resolve themselves 

 into pillars which extend from surface to surface, and are 

 more or less cylindrical. Sometimes the granules coalesce and 



