Cretaceous Gastropoda, and Pelecy^poda from Zululand. 85 
contains myriads, of microscopically line granulations arranged in 
delicate oblique lines radiating from the umbones, and in every way 
agreeing with a corresponding structure described in the original 
account. 
Dimensions (of a specimen with closed valves). — 
Length 46 mm. 
Height 30 
Diameter 25 
As stated by Mr. Etheridge this species is nearly allied to 
Pholadomya ncocomensis of Leymerie (Mem. Soc. Geol. France, 
1842, vol. 5, part 1, pi. 8, fig. 4, p. 3), and Myopsis unio'ides of 
Agassiz (Etudes Grit. Mollusques Fossiles, 1845, pi. 31, figs. 11, 12, 
p. 258), from the European Neocomian formation, both of which are 
closely related forms, being perhaps nearest to neocomensis on 
account of its slightly " donaciform " anterior end — a peculiarity 
referred to by Orbigny (Pal. Frangaise Terr. Cretaces, Lamelli- 
branchia, 1843, pi. 353, figs. 3-8, p. 329) in describing that 
species. 
It has been generally maintained by authors that Agassiz's genera 
Pleuromya and Myopsis are of similar character and should there- 
fore be united under the former name, such a result being first 
initiated by Terquem in his " Observations sur les Pleuromya et les 
Myopsis de M. Agassiz " {Bidl. Soc. Geol. France, 1853, ser. 2, vol. x, 
p. 534) ; in accordance with which Pleuroinya is used on the present 
occasion instead of Myopsis as adopted by Etheridge. 
Locality. — Tributaries of the Manuan Creek. 
Family TEREDINID^. 
Genus TEREDO, Linnaeus, 1758. 
Systema Naturae, 1758, edition x., p. 651. 
Teredo sp. 
Plate VIII., figs. 4, 5. 
Observations. — -Small masses of calcareo-siliceous rock full of 
the tubes of a Teredine mollusc probably belonging to the genus 
Teredo or one of its allied forms, have been sawn through in order 
to investigate their structure. The sections thus exposed exhibit 
the tubes both longitudinally and transversely, but only the most 
obscure traces of the valves themselves can be made out. The tubes 
appear to vary in diameter from about 6 mm. in the anterior 
region to 1 mm. at the posterior extremity. They are of somewhat 
