76 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



Dimensions : 



Antero-posteriorly . . . .20 mm. 



Dorso-ventrally . . . .9 mm. 



Locality. — Low-bottom Bed, Fulledge, Burnley. 



Observations. — From the description and figures of de Ryckholt's Gardinia 

 angulata I am inclined to refer the British forms to his species, to which I consider 

 Sir Wm. Dawson's specimen of G. angulata from the South Joggins Coal-field 

 also belongs, the specific name angulata having been given to it by him indepen- 

 dently. I have therefore referred the specimens from Burnley to this species. 

 The English examples, however, are somewhat larger. 



I have been able to examine very few specimens of this species, all of which 

 are from Burnley; and I have not met with the form from any other British 

 locality. 



It approaches somewhat the next species to be described, G. similis (Brown), 

 in the possession of an oblique ridge and the compression above it ; but the 

 general shape and dimensions have made me hesitate to refer it to this species, 

 and unfortunately at present no specimens have been found with the valves 

 closed, so that the general shape of the united valves is not known. 



14. Carbonicola similis {Brown), 1843. Plate XI, figs. 6—13, 15, 17—23, 25—27. 



Pachyodon similis, Brown. Ann. and Mag. Nat. Hist., vol. xii, 1843, p. 393, pi. xvi, 



fig. 12. 

 Unio similis, Brown. Fossil Conchology, 1849, p. 178, pi. lxxiii, fig. 9. 

 Pachyodon nanus, Brown. ADn. and Mag. Nat. Hist., vol. xii, 1843, p. 392, 



pi. xvi, fig. 1. 

 Unio nanus, Brown. Fossil Conchology, 1849, p. 177, pi. lxxiii, fig. 7. 

 Non Caedinia nana, de Koninck. Descript. Carbonif. Anim. Foss. Belgique, 1842, 



p. 71, pi. i, fig. 6. 



Specific Characters. — Shell almond-shaped, transversely oval, slightly oblique ; 

 anterior end elliptically rounded ; narrow dorso-ventrally. Inferior border 

 regularly convex, not interrupted by a sinus. Posterior end deeper than the 

 anterior, and bluntly rounded in old specimens ; but in young forms it is obliquely 

 truncate from above downwards, with a somewhat acute posterior inferior angle. 

 The superior and inferior borders are subparallel. 



The umbones are moderately convex, flattened, elongated, low, and contiguous ; 

 situated about the junction of the anterior and middle thirds of the shell. They 

 are continued downwards posteriorly to the posterior-inferior angle by a ridge, 

 above which the shell is rapidly compressed into the superior and posterior 



