ii6 
BULLETIN OF THE LABORATORIES 
SCHIZODUS TRIANGULARIS, Her, 
(Plate VI, Figs. lo, 13.) 
Macrodon ?? triangularis, Herrick. Bui. Den. Univ. vol. Ill, p. 74, Piute VIII, 
Fig. 8. 
The poor specimens encountered last year gave an entirely false 
impression of this species. We have figured two typical (but, in size, 
extreme) examples of the species which show that the specimen figured 
last year, like many others seen, had lost the narrow posterior margin. 
The description may be emended as follows : 
Shell large, sub-triangular in outline, apparently unusually thick 
for the genus. Hinge-line very short ; anterior margin nearly straight 
or even slightly concave with the antumbonal convexity apparently 
springing abrubtly from the edge, which forms a large angle with the 
hinge ; posterior margin nearly straight, very oblique to the hinges 
very near the post-umbonal ridge, post-umbonal slope very strong; 
lower outline a gentle convex curve broken by a slight sinus posterior- 
ly. Surface convex, with a shallow groove in front of the post-um- 
bonal ridge, which is strongly marked. 
The very narrow and strongly depressed post-umbonal portion is 
characteristic of the species and, as even this was hidden or broken off 
in all of our earlier specimens, the resulting form seemed quite anoma- 
lous. This species seems so unlike the associated species as to re- 
quire no comparison. It is limited to the freestone of the middle 
Waverly. 
PLEUROTOMARIA STELLA. Win? 
(Plate X, Fig. 41.) 
‘‘Shell minute, trochiform, composed of four and a half closely op- 
pressed whorls, forming an apical angle of about 90°. Suture linear, 
inconspicuous, the flat sides of the whorls all lying in the same plane. 
Body whorl regularly rounded, marked by a raised bilinear band situ- 
ated a little above the peripheral line, and on the whorls of the spire 
nearly concealed. The body whorl is ornamented by a line of minute 
tubercles running close to the suture, and occupying a feeble revolv- 
ing ridge. No indications can be seen of transverse strise connected 
with the tubercles. 
Aperture subcircular ; with the columellar lip reflected over the 
umbilicus. Some sharp incremental lines rise from the umbilical de- 
