226 
Horizon and Localities. — This is found in tlie Carboniferous Lime- 
stone of Enniskillen, Ireland ; and in the argillaceous limestone of Burragood. 
PaltEARCA interrupta, L. G. de Koninck. 
PI. XVI, Pig. 5. 
This is a small, oval, elongated shell. Its posterior side is broader than 
the anterior, which is rounder, while the opposite side is truncated .at right 
angles. The beaks are small and nearly terminal. There are two small hinge 
teeth in front of the beak, and a lateral one nearly parallel with the hinge 
line. The surface is ornamented with four or five concentric suhequi distant 
furrow’s. 
Dimensions. — The length is seven, breadth three, and thickness one 
and a half millimetres. 
Relations and Differences. — In the absence of the twm small hinge 
teeth, which are easily seen, this shell could easily he mistaken for a Modiola, 
Avhich it strongly resembles in shape. It differs from the preceding species by 
its more oval contour, and especially by the small number and the regularity 
of its furrow^s. 
Horizon and Localities. — It was found with the preceding. 
PALJ3ARCA suRARGUTA, L. G. de Koninck.^ 
PI. XVI, Pig. 8. 
This is a small, elongated, suhoval shell, tumid in the middle, and 
obliquely truncated j)Osteriorly. A square gibbosity crosses it obliquely, and 
gives rise at the hinge line to a triangular depression. The beaks are small, 
recur A’ed forwards, and situated in the anterior fourth of the hinge line. The 
hinge is composed of two small oblique teeth placed in front of the beaks, and 
of tAvo or three teeth posterior and suhparallel to the hinge line. The surface 
is ornamented with numerous concentric striae at regular distances from each 
other. 
Dimensions. — The length is twenty, breadth nine and a half, and 
thickness eleven to tAvelve millimetres. 
Relations and Differences. — This species cannot he confounded wuth 
P. costellata, because it has no radiating folds. 
Horizon and Localities. — It Avas found at Burragood. 
' \^Paran('lodony!iiihar(i)ita, R. litheridge, Jiinr. , Procs. Linn. Soc. N. S. AA’ale.s, 1SS9, lA’ (2), p. 205. — 
W.8.D.] 
