On Lingulasma, Etc. — Ulrich. 387 
were thinner and contained a smaller percentage of calcareous 
matter than the shells of those other genera. 
In the brachial valve of Binololus we have a rather strong- 
ly marked sub-cardinal scar situated in the umbonal cavity. 
This scar is represented by the convex triangular space 
marked h in figure 5. In most species of Dinoholus this part 
is impressed, but in D. transversiis Salter, it is elevated and 
of triangular form as in Lingulasma. In front of this Dino- 
holus has a large sub-rhomboidal post-median scar, with a 
longitudinal median keel in at least two species {D. trans- 
versus and davidsoni Salter.) This scar is represented in 
fig. 5, at p. Directly in front of it is the faintly traceable 
me<?mw- pair, the same again as in Lingulastna (fig. 5, aim), 
and, on each side of these, one of the well-marked laterals. 
The last scars seem to diverge posteriorly in DiiiohoUis while 
they converge in the same direction in Lingulasma. If, how- 
ever, the parallel lines marking the surface of the scars be com- 
pared it will be seen that they, at any rate, run in the same di- 
rection in both. The anteriors are not readily /lef'^rmined in 
Lingulas77ia, yet it is scarcely to be questioned that they were 
placed, as in the trimerellids generally, at the center of the 
anterior extremity of the platform. 
Lingulasma has two other sets of scars which appear to be 
homologues of two pairs found in the trimerellids : viz., the 
umho-laterals and transverse scars of Davidson and King. 
In Trimerella and Monomerella the umho-laterals are situ- 
ated very near the " crescent," but in Dinoholus they are 
placed close to the suh-cardinals and post-7nedians. Thus, 
that genus again agrees with Lingulasma (fig. 5, n). The 
transverse scars (at any rate the impressions which I have 
identified with them) occupy positions in the valves of Lingu- 
lasma much nearer their sides than is the case in any of the 
trimerellids. This difference, however, is largely accounted 
for by the comparatively greater width of the platform and 
the elongate form of the valves. 
Concerning the crescentj which seems to be one of the most 
persistent characters of the TrimerellidcB^ I cannot say that it 
is unequivocally represented in Lingulasma. In the pedicle 
valve, at least, I have not found anything that might be re- 
ferred to it ; but the small transverse ridge just within the 
