35 
CIRRUS nodosus. 
TAB. CCXlX.—Figs. l, 2 , rtrad 4 . 
C. nodosus. Min. Con. Vol. II. p. 94, tab. 141, 
jfc- 2. 
Spec. Char. Conical, acuminated ; or discoid, with 
an acuminated spiral umbo ; spire reversed ; 
whorls many, with two rows of longitudinally 
extended tubercles crossed by numerous small 
carinae. 
The description formerly given of C. nodosus applies 
to the cast of the inside, which differs considerably from 
the outside, although it retains vestiges of the most pro- 
minent marks. Externally it is a rugose shell, a few of 
the numerous small carinae becoming very prominent and 
sharp as they pass over the tubercles, and divide the 
upper row almost into two. Between the transverse ca- 
rinae fine regular elevated striae parallel to the aperture are 
distinctly visible, especially upon the lower part of each 
whorl. The whorls that occupy the smaller part of 
the spire are nearly flat, with a crenulated keel at the 
lower edge. The most remarkable circumstance attend- 
ing this shell, and which assimulates it to the genus 
Serpula, is the variable form of the spire, which is often 
a small pointed cone in the centre of a discoid base, con- 
sisting of two or three of the latter volutions : sometimes 
the conical part is larger than the discoid part, containing 
only one or two turns : and lastly, all the whorls unite 
to form a regular pointed cone, such as the figure for- 
merly given. 
I am indebted to Mr. Miller’s indefatigable researches 
for a series of specimens illustrating the above observa- 
xions, which are very interesting, and not a little per- 
plexing, since they tend to connect the Generae Cirrus 
