x“ 
VOL. XVI.(2) | INFERIOR-OOLITE ECHINOIDS 18 
un 
ARTIFICIAL KEY TO THE GENERA—continued. 
b. Pores biserial. 
Large Iamb tubercles; ambs wavy, 
containing two rows of granules ... Diplocidaris 
Iamb tubercles the same size as amb 
tubercles... ae a 1 Diplopodia 
(ii) Tubercles uncrenulate. 
a. Tubercles perforate. 
Pores uniserial ; tubercles large ec Hemipedina 
Pores triserial ; tubercles large aes Pseudopedina 
Pores triserial; tubercles small on Pedina 
4. Tubercles imperforate. : 
Pores uniserial ee i a Magnosia 
Pores triserial; peristome incisions 
feebly marked ; tubercles generally 
of uniform size 335 ws Polycyphus 
Pores triserial; deeply incised peri- 
stome; primary and secondary 
tubercles usually present... a Stomechinus 
** Anus situated outside the apical system. 
(i) Poriferous zones narrow. 
Anus marginal or infra-marginal ... Folecty pus 
Anus large; close to apex... ate Pygaster 
Ambs disjunct Me Ba Are Collyrites 
(ii) Poriferous zones broad and petaloid. 
Anus infra-marginal... sae a Pygurus 
Anus supra-marginal ise hs Clypeus 
(C. Agassizt only) 
APPENDIX II. 
ON THE CORRELATION OF THE “TOP-BEDS’ 
OF THE INFERIOR OOLITE 
BY MEANS OF THEIR ECHINOID FAUNA 
BY 
L. RICHARDSON 
The “ Top-Beds,” as I have defined them in the Cottes- 
wold Hills,? comprise the Upper 7 yigonea-Grit, Dundry 
Freestone (a trace), Upper Coral-Bed, and Clypeus-Grit : 
1 Proc. Cotteswold Nat. F. C., vol. xvi., pt. 1 (1907), pp: 71-80. 
