ao 
LINGULA. 
Gen. Coir. An equiyalved equal-sided bivalve 
shell, hinge none, the base or beak of the 
valves pointed, and united into a tendinous 
tube, serving for a ligament of attachment, 
and which extends over the valves in a mem- 
branous form, open at the front. 
LINGULA mytilloides. 
TAB. XIX.—Figures 1 and 2. 
Spec. Cuar. Ovate, anterior end slightly truncated ; 
beak indistinct. 
Nearty an inch long, and three-fifths wide, the older 
shells are flatted towards the front, with rather a straightish 
edge. Shining and of a greyish blue colour. 
These are mostly found in pairs at Wolsingham in the 
county of Durham, in a dark coloured Limestone. I am 
told they are sometimes larger than the figure. They are 
preserved so well that they have the appearance of a recent 
muscle. 
LINGULA tenuis. 
TAB. XIX.—Fig. 3. 
Spec. Cuar. Elongated, lanceolate, anterior end 
truncated. 
Asout three-eights of an inch long, and not more than 
one-third in width; flattish, with a bright shining surface, 
the anterior edge short and straight: colour reddish brown. 
This, although not unfrequent in the sandy stones which 
are so commonly found at Bognor, with the Arca barbata 
(now Pectunculus of Lam.) which is also found at the Isle 
of Dogs (see tab. 15, B. M.) has, I believe, generally been 
