172 
CEISINA. 
Reptotuhigera dorsata, Bucaille, 1890, Bry. Cret. Seine-Inf. : Bull. Soc. Sci. 
nat. Bouen, vol. xxv. p. olO. 
Retepora disticha, pars, Goldfuss, 1827. Petref. Germ. vol. i. p. 30, pi, i. 
figs. Ibg, h. 
Diagnosis. 
Zoarium of dichotomous branches, which are flat and broad ; 
the breadth ranges up to 3 or 3^ mm. The obverse face is 
convex and well rounded ; the reverse is concave. Ey 
a deepening of the concavity on the reverse face, and the 
curling backward of the lateral edges, which may nearly 
meet posteriorly, the zoarium becomes almost cylindiical with 
a hollow axis. 
Zooecia arranged in series which, for this genus, are somewhat 
irregular. The lateral series number from two or three to 
eight zooecia on each side. The transverse series are prominent 
and well spaced ; the unpaired Tervian apertures are iiTegular 
and few in number. 
Dimensions. 
Fide Pergens. 
Breadth of zoarium ... ... — 
Thickness of zoarium ... 1-1-3 mm. 
Diameter of zooecia ... ... -22--2G ,, 
Diameter of aperture ... ‘08- -09 ,, 
Distance of transverse series on 
same side ... -5--75 ,, 
B.M., D. 3601. 
3-3-0 mm. 
1-5-2 ,, 
•75 „ (average) 
Disteibtjtion. 
Danian : Faxoe and Stevn’s Klint. 
Senonian — Maastrichtian ; Maastricht, St. Pierre, Falkenherg, and Heer. 
Campanian : Eiigen. 
Santonian : L’Arche de Leves. 
Coniacian : Luynes and St. Paterne, Indre-et-Loire. 
Affinities. 
The form of the zoarium in this species is interesting fi*om 
two characters. The bending backward of the edges and partial 
concealment of the reverse surface within an almost complete tube 
gives the zoarium a Diflustrine form. If the tube had been 
completed the zoarium would have been hardly distinguishable 
from hollow Spiroporce. 
