Ii. TinIh'n Ni'tdon—FastiU from Singapore, 493 
GoNIOMVA ScUtVJSNDKI, nov. (FL XXV, Fig. 1.) 
Shell rmrrow, convex, anboylindricnl, umbo anterior, vertlofll, and 
not prominent; dorsal margin gently sloping from umbo on each 
side, anterior end rounded, posterior truncated ; sculpture consisting 
of ft regular aeries of about 1(1 V-shaped, slightly curved, oblique 
cnulte. which are elevated, rounded, fun ion lute, and divided by 
prominent mi lea lions, bearing closely - set, obscure, longitudinal 
atriaLumg; some of the coat® at the anterior end arc mi gu la ted 
in wards, 
Difflewfliflus,—Length 21 t height 7 mm. 
Tbia specimen, represented by an external view of ft left valve 
embedded in the day-matrix, is beautifully marked, the costic 
showing a delicate cord-like structure; it is of narrowly elongate 
form, and appears to differ from all other members of the genus by 
its non - prominent umbo, the presence of angulate coatm at its 
anterior end, and the fuubnlato ornamentation of the costal ribs, 
The limits of Ihe ventral margin arc not defined. 
Collector.— Mr. J. B. Scrivener. 
GOHIOMYA SiffGAPOBKNSIS, Bp, QOV* (PL XXV, Figs. 2 t 3,} 
Shell elongate, slightly convex; umbon&l region very anterior, 
obtuse, vertii^l, slightly elevated at summit; posterior dorsal margin 
oblique, Jong; interior area obliquely margined from the summit, 
ahorl, rounded ; sculpture ponaistingcf a series of V-shaped, sharply 
angulAtari coital ribs arranged beneath the umbonal area, separated 
by Hulcatious, which are finer ami closer on the anterior side and 
wider apart and divided by broader grooves posteriorly ; the ribs 
are elevated, rounded, ami slightly curved outwards; surface of 
grooves bearing fine longitudinal et nations with obscure indications 
of striae on the anterior cost®, 
Dimantwnt .—Length 32, height (from umbo to thirteenth angu¬ 
lation) 11 mm. 
Two out of the three specimens representing this form are shown 
in Figs, 2 and 3, the former, an excavated impression of ft right 
valve, being the most perfect, though deficient in ventral details; 
whilst Fig. 3 applies to ft fragmentary natural oast of a left valve in 
which the anguiated costae and the short anterior region are well 
displayed. 
This species differs from G. Senwsori in its more anterior umbo, 
its much shorter anterior area, more oblique posterior margin, and its 
less defined ornamentation* It was probably a cylindrical form 
resembling such a species as Agassizes &flnuwiya sulcata from the 
Jurassic rocks of Switzerland, which also possesses very anterior 
umboiits, but differs in having coarser ribbing and a more prominent 
iiiulmiial area, which is inclined to obliquity. In the absence of 
dental characters it is impossible to say whether the Singapore 
specimens might not belong to Tn*^onia t os some forme of that genus 
exhibit a V-shaped ribbing, such as have been described by 
fir. Kitchen from the Omnia Beds (Upper Jurassic) of India 
(I'ulseontologia Indies, 1903. eor. ix, vol, iii, p. 70, pie. vil, rill), but 
