154 
IDl:0^’EA. 
3. Idmonea cristata (Meunier & Pergens), 1885. 
Synonymy. 
Eeplotuhigera cristata^ Meunier & Pergens, 1885. Xouv. Brv. Cret. sup. : 
Mem. Soc. Roy. Mai. Belg. vol. x.\. p. 36, pi. ii. 
fig- 7- 
Diagnosis. 
Zoarium with a broad, pirmately ribbed selvage. Zooecia forming 
a compressed vertical ridge, which is very high, and has sub- 
parallel sides. 
Apertures in vertical transverse series of from 3 or 4 to from 5 
to 9. The series are re flexed at the lower end, in series 
containing the most numerous zooecia. 
Peristomes well raised, especially those at the upper end of the 
transverse series. 
Dimensions. 
Length of zoarium 
"NVidth of zoarium 
Height of zoarial ridge... 
Width of zoarial ridge ... 
Diameter of zooecia 
Diameter of aperture ... 
Pergens’ type. 
B.M., D. 7 
4-6 lura. 
0 0 mm. 
2-3 „ 
2-3 ,, 
— 
1 
— 
•8 „ 
— 
•2--3 „ 
— 
•1--15 ,, 
Distribution. 
England : 
Middle Chalk : Chatham. 
Foreign : 
Senonian — Maastrichtian : Petit-Lanaye, Limburg. 
PlGURES. 
PL YIII. Fig. 4rt. A zoarium seen from above, X 9 dia. Fig. 
45, the same from the side, X 9 dia. Middle Chalk : Chatham. 
Vine Coll. D. 712. 
Affinities. 
The zoarium figured on PL Till. Fig. 4 was identified by Tine 
as Reptofascigera alternata (Orb.), but it differs clearly from that 
species. To mention only one character, D’Orbigny’s species has 
the apertures in double series, as in Bituhigera, which alone is a 
sufficient generic distinction. The specimens Horn Chatham agi'ee 
closely with the original figure, hut the transverse series contain 
fewer zooecia. 
I. cristata differs Horn I. Jiagenowi by the gi'eater number of 
zooecia in the transverse series and the greater prominence of the 
