56 
Transactions of the Boyal Society of South Africa. 
Pecten coquandi, Peron, Desc. Mollusques Cretaces, Explor^ 
Scientif. Timisie, 1891, p. 224. 
Pecten (Neithea) quaclricostatus, H. Woods, Cretaceous Lamelli- 
branchia England, Mon. Pal. Soc, 1903, pi. 40, figs. 6, 7, 
and text figures, pp. 210-214, 
Neithea quadricostata, Douville, Bull. Soc. Geol. France, 1904, ser. 4,. 
vol. 4, p. 214. 
Observations. — The specimens referred to this species represent 
a medium-sized lower or right valve, two similar valves of larger 
dimensions and with coarser details of structure, and the remains of 
an upper or left valve exhibiting an internal view of the costae as 
they appear in the neighbourhood of the ventral border, the other 
part of the surface being covered by matrix. With the exception of 
this last specimen, which is of little or no account, the valves possess 
the characteristic details of sculpture generally associated with this 
species. Each pair of primary costae encloses three rounded ribs, the 
central of which is slightly thicker and more prominent than the other 
two. The smaller right valve, which in contour and structure is the 
best preserved, has the costal surfaces and grooves near the ventral 
margin covered with microscopically fine concentric striations, whilst 
the fragmentary auricles are also delicately striated. The two 
coarser right valves are very imperfect so far as contour is concerned, 
and no auricles can be traced, but the costal system is well displayed, 
its ornamentation consisting of concentric ridge-like lines, resembling 
sometimes a series of irregular annulations. 
Dimensions (of the right ( = lower or convex) valve). — 
Small Large 
Example. Example. 
Length 35 41 mm. 
Height 35 45 „ 
Diameter 15 20 ,, (about) 
Besides the foregoing specimens, there is a much larger one showing 
a height of about 60 mm. and a diameter through the united valves 
of 23 mm. Parts of both valves are present, the posterior area being 
well preserved and exhibiting two fine radially curved parallel ribs 
equi-distant from each other, and immediately following the large 
marginal rib, which is crossed by a series of extremely fine 
and numerous growth striations. The ordinary lateral costae are 
also well preserved in places, so that the microscopically small, 
concentric sculpture is definable with a good lens, otherwise the 
specimen is deficient in the umbonal and anterior regions. The 
lower part of the posterior auricle is present and forms a marked 
concavity in both valves. According to most authorities this species 
