80 Transactions of the Boyal Society of South Africa. 
amount of development has been possible in the hinge area of the 
smallest right valve, which discloses beneath the umbo a small 
rounded cavity or fossa in immediate connection with a postero- 
horizontal groove, which may have originally supported a ligamental 
nymph. No cardinal teeth are present, so that everything points to 
this shell being a true Pholadomya, and not a Cymella, as deter- 
mined by Mr. Whitfield (without, however, any explanation), which 
was one of Meek's sub-genera furnished with a central dentition. 
Dr. Blanckenhorn has given an excellent account of this species, 
accompanied by some good illustrations, as it occurs in several 
Syrian localities, the valves of which are perhaps not so sharply 
granulated as in the examples from Zululand, but the general struc- 
ture is the same ; that is, the elevated radial costae are deeply 
impressed by the crossing of the concentric ridges, thus producing a 
series of quadrangulations, the raised centres of which represent the 
tubercles, these being more or less sharply defined according to the 
degree of preservation of the valve. 
There are two or three species with which this Pholadomya may 
be related, although without actual specimens they are difficult to 
imderstand ; such, for instance, as P. suhdinnensis of Orbigny 
(Paleont. Frangaise Terr. Cretaces, Lamellibranchia, 1843, pi. 250, 
figs. 1-3, p. 38, and Prodrome de Paleontologie, 1850, vol. 2, 
p. 157), found in the Cenomanian of France, which possesses 
granulate costse, but only on the anterior half of the valve, the 
posterior half appearing to have only plain or smooth costse. Then, 
again, Zittel's P. granulosa {Denkschr. K. Akad. Wiss. [Wien] , 
1864, vol. 24, pi. 2, fig. 3, p. 116), which, as the name implies, 
shows a very similar structure, but according to the author the 
interior of the right valve possesses a wide apophysis beneath the 
umbones, which is not present in the valves from Zululand. Fur- 
ther, it may be mentioned that Forbes' s Cardium lucerna, from the 
Southern Indian Cretaceous, regarded subsequently by Stoliczka as 
Pholadomya caudata of Boemer, the equivalent of Corbula cBquivalvis 
of Goldfuss (see Stoliczka, Cretaceous Pelecypoda, Southern India, 
Pal Indica, 1871, pi. 2, figs. 10, 11, pi. 16, fig. 19, p. 79) from 
the European (Aachen) Cretaceous, difi'ers in its finer costse, more 
rostrate form, and in possessing cardinal teeth. Oq account of 
the presence of these teeth Holzapfel has recognised that species 
under Meek's genus Liojnstha {PalcBontograjjhica, 1889, vol. 35, 
pi. 9, figs. 4-6, pp. 150-151). 
According to Blanckenhorn and Lartet, P. vignesi has been 
collected in the Cenomanian of Algeria in company with Protocardia 
hillana and Hemiaster hatne^isis. It is recorded from similarly aged 
