SPIKOPOEA. 
259 
Aportiires in regular rings round the stems ; in young branches 
the nngs are farther apart than the diameter of the branches, 
but in older branches the rings are relatively much nearer. 
A tendency to a spiral arrangement of the apertures occa- 
sionally occurs, and near a bifurcation the rings become 
somewhat irregular (var. interrupta). 
Peristomes usually well raised. 
Dimensions. 
Diameter of branch 
Diameter of zooecia 
Diameter of aperture 
Distance of verticels 
Fide Pergens. 
•0-2 mm. 
•24--:3 „ 
•1 „ 
•75-3 ,, 
B.M., No. D. 420. 
. •5-1 mm. 
Distuihution. 
PuiTISlI. 
Ui>p' r Clialk : Chichester ; Bromley, Kent ; Magee Island, North 
Ireland. 
Middle Chalk ; Chatham. 
Fokeign : 
Danian : Stevn’s Klint, Faxoe, Denmark. 
Senonian— IMaastrichtian : ^laastricht ; Geulheim ; Ciply ; IMeudon ; 
St. Germain, near Paris; Fecamp, Seine- Inferieure ; 
Sainte-Colomhe, Manche ; Royau. 
Camj)anian : Iliigen ; Schooneu ; S. Sweden. 
Santonian : Saintes, Perignac, Pons, etc., Charente - 
Inferieure ; Cachemhach and L’ Arche de Leves, Eiire-et- 
I-oir ; Salzberg, near Quedlinburg, Hannover. 
Couiacian : Yeudome, etc., Loir - et - Cher, and Tours, 
Imyues, Saiute-Patorue, La llibochere, and done, ludre- 
et- Loire, in Craie de Villedieu. 
Tiironiau; Martigues, Bouches-dii-Rhone ; Merpins, Charente; north 
of Les Roches, and St. Rimay, Loir-et-Cher, in Craie 
marneiise ; Gross Ujezd and Lindenan, Bohemia, in 
Iser Schichteu. 
Cenomanian: 'Weisskirchlitz, Hradek, Schillinge, Rank, and Jiue, 
Bohemia, in Korycaner Schichten ; Plauen, Saxony, in 
Lower Planer ; Le Mans, Le Malagne, St. Calais, and 
.Jauieres, Sarthe ; Essen. 
Neocomiau : Sainte-Croix, Valid. 
Figijee. 
PL XI. Fig. 5. Part of a zoarium with the apertures verticillate 
above and spiral below ; X 7 dia. Middle Chalk : Chatham. 
Gamble Coll. D. 420. 
