314 GASTEROPODA OF THE INFERIOR OOLITE. 
Bibliography, §c.—It is unnecessary to repeat what has already been intimated 
with respect to this species when dealing with Cirrus Leachi. 
Description.—The following are the proportional dimensions of the shell 
figured (spire restored) : 
Length (7. e. height) . . . 32mm. 
Height of body-whorl to total feneen ‘ | 00/2: L00! 
Ratio of height to width 5 : . 62: 100. 
Opening of the spiralangle : =. gov’. 
Mean spiral angle of shell : 120°. 
Shell sinistral, conical-depressed qubdacuaaiy dale and deeply umbili- 
cated. The spire is conical-elongate, having towards its upper part an angle 
of 80°—35°. The precise apical conditions are unknown, but there is no reason to 
doubt that the earlier whorls are flat, as in C. Leachi, costate or reticulate, close 
and not turrited. 
When this earlier stage is concluded, with an entire change of shape the 
nodose character of the whorls becomes more and more conspicuous. By sudden 
bounds the whorls begin to increase outside the apical angle, and the anterior 
whorls, including the body-whorl, expand into a broad discoidal shell with 
canaliculate sutures. The ornaments in this stage are somewhat variable, but the 
main feature is a central keel at the angle of each whorl, which is grossly tuber- 
culated in connection with axial coste. 
The body-whorl expands greatly, so as partly to enclose the preceding whorl. 
It somewhat resembles a tube, angular externally, circular internally. Thick costz 
occur at regular intervals on the upper surface ; at the upper angle of the tube 
these costee thicken into a series of knots which constitute the first or uppermost 
spiral; a short distance below this is a subsidiary spiral on the flank of the shell, 
and below this again the ribs cross a clear space until they reach another spiral, 
which is subsidiary to the row of nodosities (fourth spiral) at the lower angle of 
the tube. In the base is a fifth tuberculated spiral (row of nodes) at the edge of 
the umbilicus, which is enormous both in width and depth. The aperture is 
circular, adherent, and expanding considerably towards the peristome. 
In the Coker specimens the finer ornamentation is rarely preserved, but we see 
traces of closely-set curved growth-lines decussating with extremely fine spiral lines. 
Relations and Distribution—This very remarkable species seems to stand 
alone, though probably its nearest relative is Cirrus Leachi. But I fail to detect 
in collections obviously intermediate forms. The short spire, discoidal aspect of 
the shell, and tubiform shape of the body-whorl will usually serve to distinguish 
C. nodosus from any other species of Cirrus. As far as appearances go, the 
form of this shell would seem to justify Sowerby’s idea that there was a connec- 
tion between Cirrus and Huomphalus. 
