CAEBONIFEROUS FOSSILS OF IRELAND. 87 



Anomia antiqua. M'Coy. (PI. XIX. fig. 7). 



Sp. Ch. — Hemispherical, irregular, convex; margin deflexed; surface of both valves minutely but irregu- 

 larly wrinkled concentrically ; foramen in the lower valve large, circular. 



This interesting shell occurs not unfrequently ; but as the specimens most usually shew only the dorsal 

 valve, they might be easily taken for a mass of Stromatopora; the irregvdar shape, and delicate, concentric 

 plication, heiglitening the resemblance : the discovery, however, of the perforated, attached valve, which I have 

 figured, points out its true nature. The shell is very thin. Length one inch, width the same. 



Malleus ORBICULARIS. M'Coy. (PL XIX. fig. 2). 



Sp. Ch. — Shell orbicular, slightly oblique, thick, irregular, foliaceous; anterior wing small, rounded at 

 the extremity, having a deep, angular sinus beneath it for the byssus; posterior wing, with nearly parallel mar- 

 gins, subtruncate at the extremity; surface irregularly marked by the imbricating, concentric laminee of growth. 



Some of the species oi Avicula and Malleus are so nearly allied, that in the fossil state it is sometimes 

 difficult to distinguish between their genera ; in the present instance, however, the great thickness of the foli- 

 aceous shell, and its irregularity, obviously approximate it to the Linnaean Ostrece, of which Malleus is a por- 

 tion : from all the other species of Malleus it is distinguished by the nearly orbicular form of the body of the 

 shell. Length three inches, width three inches eight lines ; length of hinge-line three inches three Hnes. 



Lima. Linn. 



Gen. Ch. — Longitudinally oval, oblique; auriculated valves gaping on one side, near the umbones; with 

 a triangular disc between the beaks, divided in the centre by a triangular, ligamentary pit ; without teeth. 



Lima alternata. M'Coy. (PI. XV. fig. 4). 



Sp. Ch. — Oblong, convex; hinge rectangular, ears slightly rounded, separated from the body of the shell 

 by a wide, shallow sinus in the margin, and a hollow from thence to the beak ; surface entirely covered with 

 very fine, sharp, undulating striae, alternately larger and smaller. 



This species is allied to the Lima prisca, INI'Coy, but is larger, less convex, and much more finely striated. 

 In the present species the striae are alternately larger and smaller, but perfectly equal, and farther apart in the 

 L. prisca. Length about eleven lines, width ten lines. 



Lima concinna. 3I'Coi/. (PL XV. fig. 6). 



Sp. Ch. — Obliquely ovate; hinge-line oblique; ears very small, without radiating striae, equal, surface ra- 

 diated with very numerous, close, fine, flexuous striae, alternately thicker and thinner ; the intervening spaces 

 being less than half the width of the ridges. 



This little shell has no very tangible characters, but is, nevertheless, quite distinct from any other mountain 

 limestone form. The ears are very small, and either smooth or slightly striated parallel with the outer mar- 

 gin ; the valves are nearly convex, and very closely striated, the striae being more nearly equal on one valve 

 than on the other ; the general outline is broadly ovate and oblique. Length five lines, width five lines. 



Lema decussata. 31' Cot/. (PL XV. fig. 3). 



Sp. Ch. — Obliquely ovate, lengthened, slightly convex ; ears very small, equal; hinge-line oblique ; surface 

 radiated, with numerous unequal, obtuse, smooth ridges, the spaces between which are strongly striated trans- 

 ersely. 



V 



