20 CARBONIFEROUS LAMELLIBRANCHIATA. 



Lkioptekia LONGiROSTKis, sp. iiov. Plate I^, figs. 14, 15. 



MoDioLA. ROSTEATA, Bvoivii. MS. iiomen micUun. Shell in Manchester Museum, 

 tbe Owens College. 



Specific Characters. — Shell aviculoid, small ; obliquely tumid, rliomboidal, with 

 a very long rostrum. The anterior end is almost obsolete, compressed, the antero- 

 superior angle a right angle ; its border descends less obliquely than in other 

 species ; it is slightly convex ; the lower border is convex, curving upwards behind 

 to join the concave posterior margin. The hinge-line is straight, much produced, 

 Avith a rolled rostrum, which extends far beyond the margin of the shell. The 

 umbones are tumid but small, not raised, placed very far forwards, not terminal. 

 The posterior wing is compressed, triangular, and elongate, gradually compressed 

 from the body of the valve, which is regularly and obliquely swollen, but becomes 

 compressed and expanded below and behind. 



Interior. — The hinge-plate appears to be normal ; other details not yet observed. 

 Exterior. — The surface is ornamented with smooth, concentric, somewhat 

 irregular, rounded ribs and folds. 



Dimensions. — PI. IV, fig. 14, from the Black Limestone below Mam Tor, 

 (^astleton, measures — 



Antero-jDOsteriorly (including length of rostrum) . 23 mm. 



Dorso-ventrally . . . .8 mm. 



From side to side . . . .7 mm. 



LocAtlUies. — England: the Pendleside series of Castleton, Derbyshire; Tod- 



morden, (? Horsebridge Clough, Hebden Bridge) ; Flasby Fell and Pendle Hill, 



Yorkshire ; Congleton Edge, Cheshire. 



Observations. — Two specimens in the Manchester Museum, Owens College, 

 labelled Todmordon, have the MS. name Mod tola rostrata, a nomcn. iinrhun, and 

 luifortunately de Koninck has adopted this specific name for another shell, so that 

 I am unable to adopt Captain Brown's name. 



The specimens have not the characteristic rostrum preserved, but it seems 

 evident from the name that Captain Brown had oljserv^ed this character. The 

 most perfect specimens, PI. IV, fig. 14, come from the Black Limestone below 

 Mam Tor, near Castleton, and I have obtained the shell at several other places on 

 the same horizon. L. longirostris occurs in the zone of rosidonom/ya Bccheri and 

 (Uyphioceras spivde, G. reticnlatmn, and G. hilinffue, and as far as I know is confined 

 to that zone. Tlie shell, when detached from the posterior wing, might l)e 

 mistaken for I'osidoiiicUa minor, a species which is often found in association with 



