42 
TUE GEOLOGIST. 
out by Dr. Mjintell in his original description of the species, and 
serves to distinguish it from another form, nearly equally common in 
the chalk, which is figured and described by Goldfuss as C. granulosus, 
but is generally regarded as a (perhaps sexual ?) variety, having a more 
tumid shell, and with the additional rows of tubercles on the upper 
surface rudimentary or obsolete. 
Tlie pairs of ambulacral pores in Cypliosoma Koe7iic/i, form ten wind- 
ing lines from the mouth-opening {peristome) to the apical orifice 
{periproct). They are somewhat crowded at the mouth, but extend 
in single file to a little above tlie circumference, and then fall into 
double series on the upper part of the shell. The specimen repre- 
sented by fig. 1 exhibits a portion of the dental apparatus, lying in 
the peristome, and consisting of one of the five pairs of jaws which are 
similar in all the EcMnidce, and form the ' lantern' of Aristotle. 
Young and half-grown specimens of Cyp'hosoma Koenigi are com- 
paratively rare. They may be recognized by the flatness of the under 
surface, which distinguishes them at all ages, while in the little C. 
corollare (Parkinson) the base is rendered concave by the curling in- 
w'ards of the margin of the peristome. In the other common little 
species, C. spatullferum (Forbes), the ambulacral pores are ranged in 
single file throughout their course. 
The spines of Cypliosoma Koenigi are awl-shaped and rather short 
and stout, with spatulate ends. In the second example figured, a 
multitude of spines of all sizes were preserved in connexion with the 
shell, and have been cleared from the matrix with great skill and in- 
genuity by Mrs. W. H. Allen. 
There is another specimen in the British Museum with the spines 
remaining in situ, which was obtained more than a century ago, and 
formed one of the ornaments of Sir Hans Sloane's collection. 
Although common in the chalk-pits of the Thames Valley, and in 
those near Brighton and Lewes, the Cypliosoma Koenigi appears to be 
unknown to the collectors of fossils from the uppermost division of 
the chalk at Norwich, or in the corresponding bed at Ciply in Bel- 
gium, and Meudon near Paris. It is said to be found at Montolieu, 
in the department of Drome, at Dusseldorf, and in the island of Rugen 
in the Baltic. 
