328 ME. HEEBEET BOLTON ON [Aug. 1 9 I I ? 



well marked, although the shell itself is as thin as tissue-paper. 

 Examples of this species were also found in a heavy black bitu- 

 minous shale with plant-remains, forming ' Horizon 4,' at about 

 138 feet below the Bedminster Great Vein at the same colliery. 

 In the roof -shales of the High Yein, in the Parkfleld Series of the 

 Upper Coal-Measares at Coalpit-Heath Colliery, the remains of this 

 species are rarely in anything like good condition, although portions 

 of shell are met with frequently, the part most often preserved 

 being the posterior ventral margin. In the two best specimens 

 found, the length along the antero-posterior diagonal is 20 mm. 

 The small anterior end is not easily distinguished, but the straight 

 hinge-line and shell-margin are perfectly clear. No evidence of 

 tumidity is present — the valves lying flat upon the shale, and 

 showing the somewhat irregular and unequal lines of growth. 

 The periostracum is usually present and much wrinkled. 



Dr. Wheel ton Hind records this species from the Lower Coal- 

 Measures of the Speedwell Pit, Kingswood (Gloucestershire). 1 The 

 discovery was made by the late Mr. Stock, but the horizons were 

 not determined. At Writhlington Colliery in the Padstock district, 

 Mr. D. M. Watson, of Manchester University, found several fine 

 •examples on the spoil-heap, and others have since been collected 

 by me. Most of the forms at this colliery have the valvular ridge 

 much more oblique and pronounced than in specimens figured by 

 Dr. Wheelton Hind in his monograph, while elongated examples 

 are not uncommon. In the latter forms, the hinge-line is long and 

 the posterior ventral border expanded. The umbo in the Writh- 

 lington specimens is tumid, and in well-preserved examples slightly 

 overhangs the hinge-line. The shells occur in a soft black shale 

 with ironstone bands, which splits up very irregularly. The 

 horizon is not known. 



At Poxcote Colliery, the examples of this species are found in 

 shales of the Second Series of the Upper Coal-Measures, and are 

 unusually well preserved for so fragile a form. The wrinkles of 

 the periostracum follow in the main the concentric lines of growth ; 

 but this is not always the case, examples being found in which 

 the wrinkles are at right angles to the lines of growth, or form 

 an irregular meshwork. Uncrushed shells are fairly numerous, 

 and even in those which are crushed the umbones still retain some- 

 thing of their tumidity. The rock is a dark shale, breaking irregu- 

 larly, and containing irregular masses of dark-brown material much 

 similar to coprolitic matter. A few ostracods are scattered through 

 the shale. 



Anthracomya phiWpsi was also obtained from the roof-shales of 

 the Easton Great Vein at Easton Colliery. It presents no features 

 of special interest, occurring sparingly in a compact black shale, 

 which is well-bedded. The Easton Great Vein of the Lower Coal- 

 Measures has been correlated with the Kingswood Great Vein. 



1 ' Carbonicola, Anthracomya, & Naiadites ' Pal. Soc. Monograph (1894-96) 

 p. 121. 



