E. BuUen Newton — Fossils from Singapore. 493 



GoNioMYA ScRiVENORi, sp. nov, (PI. XXV, Fig. 1.) 



Shell narrow, convex, subcylindrical, umbo anterior, vertical, and 

 not prominent ; dorsal margin gently sloping from umbo on each 

 side, anterior end rounded, posterior truncated ; sculpture consisting 

 of a regular series of about 16 V-shaped, slightly curved, oblique 

 costse, which are elevated, rounded, funiculate, and divided by 

 prominent sulcations, bearing closely - set, obscure, longitudinal 

 striations ; some of the costge at the anterior end are angulated 

 inwards. 



Dimensions. — Length 21, height 7 mm. 



This specimen, represented by an external view of a left valve 

 embedded in the clay-matrix, is beautifully marked, the costae 

 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 C08t» at its 

 anterior end, and the funiculate ornamentation of the costal ribs. 

 The limits of the ventral margin are not defined. 



Collector. — Mr. J. B. Scrivenor. 



GoNiOMTA SiNGAPOEENSis, sp. nov. (PI. XXV, Figs. 2, 3.) 



Sliell elongate, slightly convex ; umbonal region very anterior, 

 obtuse, vertical, slightly elevated at summit ; posterior dorsal margin 

 oblique, long ; anterior area obliquely margined from the summit, 

 short, rounded ; sculpture consisting of a series of V-shaped, sharply 

 angulated costal ribs arranged beneath the umbonal area, separated 

 by sulcations, which are finer and closer on the anterior side and 

 wider apart and divided by broader grooves posteriorly ; the ribs 

 are elevated, rounded, and slightly curved outwards ; surface of 

 grooves bearing fine longitudinal striations with obscure indications 

 of striae on the anterior costae. 



Dimensions. — 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 a right 

 valve, being the most perfect, though deficient in ventral details; 

 whilst Fig. 3 applies to a fragmentary natural cast of a left valve in 

 which the angulated costae and the short anterior region are well 

 displayed. 



This species difiers from G. Scrivenori 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 Agassiz's Goniomya sulcata from the 

 Jurassic rocks of Switzerland, which also possesses very anterior 

 umbones, but differs in having coarser ribbing and a more prominent, 

 umbonal 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 Trigonia, as some forms of that genus 

 exhibit a V-shaped ribbing, such as have been described by 

 Dr. Kitchen from the Oomia Beds (Upper Jurassic) of India 

 (Palseontologia Indica, 1903, ser. ix, vol. iii, p. 70, pis. vii, viii), but 



