42 



TUE GEOLOGIST. 



out by Dr. Mantell in his original description of tlie species, and 

 serves to distinguish it from another form, nearly equally common in 

 the chalk, which is figured and described b}^ 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. 



The pairs of ambulacral pores in CypJiosoma Koenigi, form ten wind- 

 ing lines from the mouth-opening {jperistome) 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 EcMnidcs, and form the ' lantern' of Aristotle. 



Young and half-grown specimens of Ctjplwsoma 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- 

 wards of the margin of the peristome. In the other common little 

 species, G. spatuliferum (Forbes), the ambulacral pores are ranged in 

 single file throughout their course. 



The spines of CypJiosoma 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. AY. 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 A^alley, and in 

 tliose near Brigiiton and Lewes, tlie Cgpliosoma Kwnigi appears to be 

 unknown to the collectors of fossils from the uppermost division of 

 the chalk at Norwicli, 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 Dusseklorf, and in the island of Eugen 

 in tlie Baltic. 



