176 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



the characteristic form of the anterior end and the subparallel margins appear to 

 me to be typical of A. Wardi. 



Dr. Young tells me that these are the only shells of this species known from 

 this locality, and that he has not met with this form before. I have no hesitation 

 in referring them to the genus Anthracomya, and to the same species as figs. 13 

 and 15 of PI. XIII, although the Possil shells are so much finer than any others. 

 Conditions must have been extremely suitable for the growth and development of 

 the shell in this locality, and it is remarkable that no more specimens are to be 

 met with in Scottish collections. Dr. Young informs me that crushed forms of 

 Naiadites, probably N. modiolaris, occur with this shell, and that Lingula sqiiami- 

 formis also is found in bands of black shale in connection with the Possil Lower Iron- 

 stone, but that Naiadites and Lingula never occur in exactly the same stratum. 



Of Dr. Young's two specimens one is very much larger than the other. The 

 finer example (PI. XXI, fig. 9) is, however, somewhat crushed and imperfect at 

 the anterior end, and does not show the typical form of the shell so well as the 

 other (PI. XXI, fig. 10). 



This shell measures — 



Antero-posteriorly . . . .66 mm. 



Dorso-ventrally at umbo . . . 23 ,, 



Laterally . . . . . 15 „ 



Anthracomya Phillijjsii (p. 120). — PI. XXI, fig. 7, is a non -compressed 

 example of this species from the Upper Coal-measure shales. Speedwell Pit of the 

 Gloucestershire Coal-field. Typical compressed examples occur in the same 

 shales. 



Anthracomya dolohrata has also been obtained from the Lancashire Coal-field ; 

 two specimens, of which I figure one, fig. 13, are assuredly young. 



16. Anthracomya subpakallela, Portlock, sp., 1843. Plate XVII, figs. 1 and 2 ; 



Plate XXI, figs. 2—6. 



MoDioLA suBPABALLKLA, FortJock, 1843. Eeport Geology County Loudon- 



deiTj, &c., p. 43.3, pi. xxxiv, fig. 16. 

 — _ Morris, 1843. Catalogue of British Fossils, p. 92. 



? Caruinia sijbpaballela, Keyserling, 1846. Petscbora Land, p. 255, pi. z, 



fig. 15. 



— — d'Orbifftii/, 1850. Prodrome de Paleontologie, p. 131. 



— — Eiehioald, 1860. Lethfea Rossica, 2nd part, p. 1007. 

 MoDiOLA Macadaiiii, Bail}/, 1875. Figures of Characteristic British Fossils, 



p. 114, pi. sxxix, fig. 6. 



