512 BRITISH PALAZOZOIC FOSSILS. (LAMELLIBRANCHIATA. 
This beautiful species is of the general form of Leda, but I have formerly seen specimens with the pallial 
line entire. Prof. Phillips probably overlooked Prof. Fleming’s description, and identified the species with 
the Liassie NV. claviformis of Sowerby, which it somewhat resembles in form. I have seen the hinge-teeth of 
this species, but mark the genus with doubt, as I have not satisfied myself as to whether there is or is not a 
cartilage pit beneath the beaks. 
Position and Locality —Common in the carboniferous shale near Glasgow. 
NucuLa cLAvata (M'Coy). 
Ref—M ‘Coy, Synop. Carb.’ Foss. Trel. t. 11. f. 25. 
Desc.—Ovate or subclavate, moderately gibbous; beaks moderately prominent, obtuse, anterior lunette 
ovate, narrow; anterior end moderately large, obtusely rounded ; posterior end nearly twice the length of the 
anterior, very obtusely rounded at the pointed extremity, no posterior slope, the cardinal edge being rather 
tumid; ventral margin most convex in the middle, much less so towards the anterior and posterior ends: 
valves moderately convex, most so in an oblique line from the beak to the middle of the ventral margin, from 
whence the valves are gently compressed towards the extremities. Surface marked with very fine, obtuse, sub- 
equal, concentric strize (fifteen in one line at four lines from the beak), and a few stronger parallel interrup- 
tions of growth. Length about eleven lines (large specimen), proportional width from beak to opposite ventral 
margin *4, length of posterior end from beak ;;;, length of anterior end from beak ;;,, depth of both valves 5. 
This species is intermediate between the Vucula attenuata Flem. and N. Phillipsi M°Coy. It is distin- 
guished from JV. attenuata by the much shorter and more obtuse posterior end, and from both species by the 
absence of any trace of the posterior slope. M. D’Orbigny in his Prodrome, p. 129, places this species in the 
genus Leda, but I have no reason for thinking there is any sinus in the pallial impression. I have seen the 
hinge-teeth very obscurely. 
Position and Locality—Rare in the carboniferous shale of Glasgow. 
NucuLa aipposa (f/em.) 
Ref. and Syn.—Fleming, Brit. Anim. p. 403.= Nucula tumida Phill. Geol. York. Vol. II. t. 5. f. 15. 
Dese.—Ovato-oblong, very gibbous, most so about the middle, from whence the surface arches in all direc- 
tions; beaks very tumid, much incurved towards the anterior end; anterior end very small, contracted, only 
extending slightly in front of the beaks; a large deep cordate depression beneath the beaks; posterior end 
moderately lengthened, semielliptically rounded, no defined or flattened posterior slope, ventral margin nearly 
straight at the anterior end, very convex a little behind the middle, and arching then upwards towards the 
posterior end. Surface with numerous fine, concentric, thread-like lines of growth (eight in one line at two lines 
from the beak), and a few stronger interruptions of growth near the margins ; hinge-teeth numerous, interrupted 
at the beak by the cartilage-pit. Length from anterior to posterior end seven lines, proportional width from 
beak to same point %, greatest width at right angles to middle of hinge-line ;, depth of both valves 5. 
The great gibbosity easily distinguishes this species from the other palzeozoic forms. M. D’Orbigny in his 
Prodrome, p. 130, places this species in the genus Cypricardia, but I have clearly ascertained the presence of 
the angulated line of hinge-teeth, and the intermediate cartilage pit of Nucula. 
Position and Locality —vV ery common in the carboniferous shale of Glasgow, common in the carboniferous 
shale of Craige, near Kilmarnock. 
Nucuta LucrniForMIs (Phill.) 
Ref—Phill. Geol. York. Vol. II. t. 5. f. 11. 
Desc.—Subovate, beaks tumid, oblique, moderately prominent, having an obscure cordate depression in front 
of them; anterior end short, regularly rounded ; posterior end obliquely subtruncate, very slightly convex; anal 
