182 SUPPLEMENT TO THE CRAG MOLLUSCA. 
CANCELLARIA UMBILICARIS P Broccht. Addendum Plate, fig. 10. 
VoLuTA UMBILICARIS, Broc. Conch. Foss. Subap., vol. ii, p. 312, tab. il, figs. 10, 11. 
CANCELLARIA — Bellardi. Foss. de Piemont., p. 36, tav. iv, figs. 17, 18. 
Spec. Char. “C. Testa ventricosa, anfractibus, scalariformibus, canaliculatis, longitu- 
dinaliter costata, profunde transversim sulcata, sulcis subimbricatis crispis, umbilico patent- 
issimo, usque ad apicem spire pervio. —Broc. 
Locality. Red Crag, Waldringfield. 
The Rev. H. Canham has sent to me for representation a very perfect specimen which he 
has obtained from the Red Crag at Waldringfield, and this I have referred as above, with 
some doubt, as it does not strictly conform to any of the figures representing the foreign 
specimens under the name of C. wméilicaris, Our shell may probably be a dwarf 
variety of this species, with a depressed spire. 
Our present’ specimen, there can be no doubt, is merely present as a derivative in the 
Red Crag, but whether it be derived from the Coralline Crag or from some older bed, 
there are not at present the means of judging. 
I have from the Cor. Crag a very imperfect specimen belonging to this genus, 
which is distinct from any other that I have previously described, but it is too imperfect 
for representation. It somewhat resembles C. elongata, Nyst. 
Cancellaria subspinulosa, Supplement ‘ Crag Moll., Pl. VI, fig. 10, may possibly be 
the young ©. dyrata, Broc., but better specimens than I possess will be required for its 
determination. 
PyRaMIDELLA LavinscuLa, S. Wood. Crag Moll., vol. i, p. 77, Tab. IX, fig. 2. 
Supplement, p. 07. 
Mr. Jeffreys has kindly sent to me for examination some recent specimens obtained in 
the Mediterranean, and from his deep sea dredgings, which he considers identical with 
my Crag shell. On comparison I find the recent specimens more conical in shape, and 
more resembling P. conulus, Speyer (‘Die Conch. der Cass. Tertiar.,’ Tab. XXV, fig. 1. 
In his letter Mr. Jeffreys says, “There is some difference between the Porcupine and 
Crag shells, which I consider varietal only, consequent on some alteration in the conditions 
of habitat. I make some allowance for the great lapse of time and subsequent change of 
form.” The lapse of time and alteration of conditions are, I believe, the main causes 
operating to produce new species, and inasmuch as the more our knowledge of recent 
and fossil forms extend, the greater will be the perplexity among paleontologists where 
to draw a line of specific distinction, and the more will they be driven for classification 
