113 
FECTUNCULUS umbonatus, 
TAB. CCCCLXX1 l.—fig. 3. 
And TAB. CLV1 .—Jigs, 2, 3 and 4. 
Spec. Char. Orbicular, gibbose, nearly iequi~ 
lateral, longitudinally striated and obscurely 
costated; beaks prominent, obliquely curved* 
a lobe on the anterior side. 
This is the same shell given as a Cardium at page 128 
pfVol. II. because the hinge had not then been seen. It 
is distinguished from P. sublsevis just described, by the 
prominent beaks, and smaller number of its ribs; the 
teeth are large in proportion to the shell, from which 
circumstance it should seem to be the Fectunculus men- 
tinned as found in the Whetstone-pits by Parkinson, 
VoL III. p. 169. I am indebted to Mr. Goodhall for 
specimens shewing the hinge. It occurs both at Hall- 
down and Blackdown. 
FECTUNCULUS scalaris. 
TAB. CCCCL 2. 
Spec. Char. Obovate, convex, longitudinally 
ribbed, ribs narrow, sharp ; area of the 
ligament short, projecting at the extremi- 
ties, with a triangular pit in its centre \ 
margin irregularly toothed. 
Externally this is marked exactly in the same way 
as P. costatus,* (tab. 27, fig. 2,) the transverse lines 
between the ribs resembling the steps of a rope ladder. 
The length exceeding considerably the breadth, the 
granulated rather than toothed margin, and the triangular 
pit in the hinge, are strong marks of distinction that can- 
not easily be overlooked; the teeth of the hinge are long 
and sharp, like those of N'ucula, to which genus the 
hinge altogether bears a strong resemblance: the hinge 
of A rea aurita of Brocchi is similar. 
Sent by Miss Beminster from Hordwell ; it has often 
been confounded with Blunders Area deleta. 
* This is Area deleta of Brander, consequently it should have been 
called Pectunculus deletus. 
