Oarhoniferoics Fossils frovi Siam. 119 



Wheelton Hind says it has a rounded anterior ear and a compressed 

 expanded posterior ear. The anterior ear is well seen in our complete 

 specimen, which has both valves preserved, and in this example the 

 ear seems relatively wider and larger than in the other specimens. 

 In the largest shell the umbo seems subterminal, and the whole shell 

 more elongated and less rhomboidal. Distortion often afiects the 

 shape of specimens of Posidonomya, and some of the difficulties and 

 differences of opinion with regard to its characters result from this 

 cause. There is a shell figured by De Koninck as P. plicata ^ which 

 bears much resemblance to our specimens, and the Culm shells 

 from North Devon, which Phillips^ figured and described as 

 P. Becheri and P. lateralis Sow. may also be compared. Diener'' 

 has referred some indistinct casts in the Anthracolithic beds of 

 Spiti to this genus, but otherwise it does not seem to have been 

 recorded from the Carboniferous of Asia. 



The discovery of specimens of this shell at Kuan Lin Soh in 

 a rock precisely similar to that of the image from Bah Nah, and 

 their occurrence in the same rock as the rest of the fauna, fixes 

 the age of the specimens in the image. 



Posidonomya (?) cf. radiata Wh. Hind. 



There is an imperfect impression of the greater part of the left 

 valve of an obliquely ovate shell about 11 mm. high, with a gently 

 convex surface marked by fine concentric lines and straight, 

 radiating, broad ribs which are of rather unequal strength and 

 width, being sharp, narrow, and strong near the posterior margin, 

 but low and weak in the middle. So far as its characters can be 

 determined, there is a resemblance of this shell to Posidonomya 

 radiata Wh. Hind,^ but the generic reference of this species seems 

 open to doubt. 



Pseudamusium cf. prcetenue Von Koenen. (PI. II, Fig. 8.) 



There is one right valve of a species of a pectinoid shell represented 

 in the collection by an internal cast and external impression, which 

 resembles Pecten jorcetenuis Von Koenen '" from the Culm of Germany. 

 It measures 13 mm. in length and 10 mm. in height. In shape it is 

 obliquely oval and very inequilateral ; the beak is small, acutely 

 pointed, directed forwards, and subanterior in position. The body 

 is nearly flat and well marked off from the narrow elongated 

 depressed jDosterior ear, which reaches about half-way down the 

 posterior margin. The anterior edge of the shell is strongly arched 

 forwards below the very small jDrojecting anterior ear, which seems 



^ De Koninck, op. cit., p. 182, pi. xxxix, fig. 8. 



2 Phillips, Palceoz. Foss. Cornw. Dev., 1841, pp. 44-5, pi. xx, figs. 73-4. 

 ^ Diener, Perm. Foss. Centr. Himal. : Palceont. Ind., ser. xv, Himal. Foss., 

 vol. i, pt. V, 1903, p. 138. 



^ Wlieelton Hind, op. cit., p. 31, pi. vi, figs. 6-9. 



i^ Von Koenen, Neues Jahrb. f. Min. Geol, 1879, p. 329, t. vi, figs. 3, 4. 



