On some West-Australian Entomostraca. 31 
0.74 mm. This form accordingly grows to a rather larger 
size than the species of Cypr'inotus described above. 
Seen from the side (Pl. 4, fig. 6), the shell exhibits a 
somewhat irregular oblong reniform or slightly clavate shape, 
with the greatest height not nearly attaining half the length, 
and occurring considerably in front of the middle. The 
anterior extremity appears broadly and regularly rounded, 
whereas the posterior one is considerably narrower and 
terminates in a slightly deflexed, obtuse prominence. The 
dorsal margin is gently arched, with its greatest curvature 
somewhat behind the ocular region, from whence it declines 
with a nearly straight course to the front edges. In its 
most posterior part it exhibits an indication of a sinus just 
above the obtusely produced hind extremity, The ventral 
margin is evenly concaved a little in front of the middle, 
and joins the anterior and posterior edges without any 
intervening angle. | 
Seen from above (fig. 7), the shell appears moderately 
tumid and oblong fusiform in outline, with the greatest 
width about equalling 2/5 of the length, and occurring some- 
what in front of the middle. The lateral contours are quite 
evenly curved, and both extremities pointed, though the 
posterior one is considerably narrower than the anterior. 
The valves are nearly equal, though, on a closer exa- 
mination, the left one is found to overlap the right at both 
extremities by a very narrow, hyaline border. The edges 
of both valves are perfectly smooth, and the inner duplica- 
tures rather narrow. 
The surface of the shell is smooth and polished, with- 
out any obvious sculpturing, and it is clothed at each extremity 
with seattered short hairs. 
