NEWTON: MALAY TRlASSIC r-ELECYPODA. 131 



characteristic of the Rhoetic or uppermost Trias. It is to this 

 horizon, therefore, that the Myophorian Sandstone from the Malay 

 Peninsula must he referred. 



DESCRIPTIONS OF THE SHELLS. 

 1. Chlamys Yaloniensis (Def ranee), Leymerie. PI. XII, Fig. 1. 



Pecten Faloniensis, Defrance : in De Caumont's " Sur quelques 

 terrains de la Normandie Occidentale," Mem. Soc. Linn. 

 Calvados 1 (Caen), vol. ii (1825), p. 507, pi. xxii, fig. 6 

 (imperfectly figured and without description). Leymerie : 

 Mem. Soc. "geol. France, vol. iii (1838), pt. 1, pp. 346 & 

 347, pi. xxiv, fig. 6. Portlock : Geol. lleport Londonderry, 

 1843, p. 127, pi. xxv a, figs. 14, 15. Moore : Quart. 

 Journ. Geol. Soc, vol. xvii (1861), p. 501 ; op. cit., 

 vol. xviii (1862), pi. xvi, fig. 6. Stoliczka : Mem. Geol. 

 Surv. India, vol. v (1865), pt. 1, pp. 44, 75. Griesbach : 

 Records Geol. Surv. India, vol. xiii (1880), p. 95. 



According to Leymerie, this shell is characterized by the presence 

 of smaller ribs, disposed irregularly between the larger ones ; by its 

 transversely striated ribs ; and by its ears being ornamented with 

 vertical lines. The specimen referred to this species appeals to be an 

 internal impression of a right valve, showing an excellent contour, 

 although part of the ventral margin is absent. It is covered with 

 numerous radial costa3 with faint indications of fine concentric striae, 

 some smaller intermittent ribs being also traceable. The auricles, of 

 unequal size, are distinctly ornamented with thin vertical striations. 



Dimensions. — Height 65, length 55 mm. 



The species is here recognized under the genus Chlamys, Bolten, on 

 account of its radially sculptured surface, valves of nearly equal size 

 and convexity, and possessing a well-marked byssal orifice. 



Distribution. — Characteristic of the Rhaetic division of the Triassic 

 series of England, Ireland, Europe, India, etc. ; it occurs also in the 

 Lower Lias (Calcaire de Yalognes-Hettangian Beds) of Normandy, etc. 



2. Pteria Pahangensis, n.sp. PI. XII, Figs. 3, 4, 5. 



Three internal casts of left valves, belonging apparently to the 

 same species, are here referred provisionally to the genus Pteria 2 



1 This reference has been wrongly quoted by some authors as "Ann. Soc. Linn. 



Normandie." 



2 It may be here pointed out that Klein's name of Avicula, 1753, being pre- 



Linuean, is not admissible, although adopted by Bruguiere in 1792, Scopoli 

 having founded his genus Pteria in 1777 (Introd. Hist. Nat., p. 397) on the 

 same type, viz. Mytilus hirundo, Linnaeus. Gray adopted this rendering in 

 1847, and replaced the family name of Aviculidae by Pteriadae (Proc. Zool. Soc, 

 1847, p. 199), a plan which has since been followed by Meek in 1876, and by 

 Dr. Dall at the present dav (see Eastman's edition of Zittel's " Text-Book of 

 Palaeontology," 1900, p. 370). 



