CRISIS A. 
175 
Apertures in series of four' or five ; the series are suhalternate. 
The median unpaired series is veiy irregular, and the 
irregularity in places affects the innermost of the serial 
zooecia. Peristomes well raised. 
DlilEXSIOXS. 
Diameter of branch 
Diameter of zooecia 
Diameter of aperture 
Distance of the series of apertures 
•8-1 mm. 
•17 „ 
■07--12 ,, 
DisTEiBrnoN. 
Middle Chalk : Chatham. 
Figure. 
PL IX. Fig. 9. The obverse face of a zoarium, x 12 dia. 
Middle Chalk : Chatham. Gamble Coll. D. 4069. 
Affinities. 
The specimen, on which this species is founded, was sent by 
^Ir. Gamble to M. Pergens, who added in a manuscript note on the 
back of the slide : “not Idmonea cypris, d’Orb. I think n.sp.” The 
foiTo differs from Eetecava cypris by the lateral compression of 
the branches ; but the essential difference is that in I. cypris the 
rows of apertures are far nearer together and more regular. This 
Biyozoan is nearer to Crisina (^Tervia) dorsata, but differs frem it 
by the naiTowness of the reverse surface and less regular arrange- 
ment of the apertures. It also agi’ees in some respects with Tervia 
■Mueller i (Beissel), in which, however, the lateral apertures are 
fewer and the series are more widely separated. 
D. 4069. Three fragments (on slide). Middle Chalk. Chatham. Gamble 
Coll. Figd. PI. IX. Fig. 9. 
FX^REPBESEXTED AXTD DOUBTFUL SPECIES. 
1. decurrens (Pocta), 1892. 
Syx. Idmonea decurrens, Pocta, 1892. Mech. Koryc. Hoiy: Ceska Ak. Fr. 
Jos. Praze, sect. ii. p. 18, pi. ii. figs. 3-6. 
Char. — Zoarium of simple triangular branches. Apertures in alternate pairs 
and triplets with a regular median series. Peristomes low. 
Distrib. — Cenomanian : Kauk, Bohemia. 
