THE KNOTTED WEDGE-COKAL. 
327 
just within tho wall, ami tlicuce gradually becoming thinner. The primariec 
and secondaries equal in height and breadth ; the tertiaries much lower ; 
all salient, the upper edge obliquely truncate, sloping down from the 
margin inward. The two plates which form the short axis are united 
to the columella by diverging lamina) ; but this structiu-e appears to be 
wanting in the others. The surfaces of all the plates are rough, with 
.scattered papillary points. 
Columella. Bent at each end towards one (the same) side ; its upper 
edge thickened iii 
irregular swellings. 
In .some .specimens 
it is not visible 
iVom above. 
NO. 
Size (of four examples). 
LONG AXIS. SHOUT AXIS. 
HEIGHT. 
1 . . 
. O’OS inch . . . 
0-062 .... 
0-155 
2 
. 0-06 „ . . . 
0-042 .... 
0-140 
3 . . 
. 0 06 „ . . . 
0-050 .... 
0-110 
4 . . 
. 0 06 „ . . . 
0.042 .... 
0-144 
Ani.mal. Unknown. 
Locality. 
North-cast coast of Ireland ; deep water. 
I'his species resembles S. crispus in its zig-zag folds, 
but lias more agreement witli S. mixtus in its general 
eliaracters. In its tendency to a curyed form, however, 
as well as in its pedicellate cliaracter, and especially in 
t!ic presence of a well-formed basal area, wliicli appears 
to have been a point of adhesion, it displays so much 
affinity with Ceratotrochus (according to the diagnosis of 
^lilne Edwards) that I was at first disposed to assign 
it to that genus. 
The four specimens that I have above described Iiavc 
been entrusted to me by my kind friend, Ur. E. Perceval 
Wright, of the Uiiblin University, with whose name 1 have 
honoured the species. They were dredged by G. C. Ilynd- 
man. Esq., among shell sand, from a turbot bank off the 
coast of Antrim, in 1852. 
I have introduced the tiny form into this work, believing 
it to be an existing, and not a fossil species. Professor 
