122. W.D. Lang—Cretaceous Polyzoa of the Family Idmoniide. 
VI.—A Tasutar View oF THE CreETACEous PotyzoAa OF THE “Famy 
IpMontrID&. 
By W. D. Lane, M.A., F.Z.8., F.G.S., of the British Museum (Natural History), 
ia the Gxrotocican Magazine for 1906! a key of. the published 
figures of the Cretaceous forms referable to the genus Hntalophora 
was offered in the hope that by means of it the difficulties attendant 
on the determination of the species of this genus might be obviated. 
A similar key. was prepared for the difficult genus Retecava; but in 
its preparation it was found necessary to overhaul other genera of the 
family Idmoniide, a work which resulted in reducing all the genera 
of this family to a tabular form for the Aeneemtuatien of the species. 
These tables are here given for the use of the collector in determining 
the forms and as a guide to the descriptions in the British Museum 
Catalogue. 
I. Tue GENERA COMPRISING THE IDMONIIDZ. 
The Tdmoniidee are defined as Cyclostomata Tubulata in which 
there is a ‘reverse face’ of the zoarium without apertures, and those 
on the ‘obverse face’ are arranged in rows symmetrically about the 
middle line. 
Like other families of Cretaceous Polyzoa, the Idmoniide include 
encrusting and branching forms which pass in regular sequence from 
strap-shaped zocecia through discoid to erect forms. There is no 
foliate genus like Diastopora? among the Diastoporide. The simplest 
genus, iSinaiecr resembles forms of P roboscina such as P. radiolitorum 
and P. anomala; the former, as pointed out by Gregory,® being 
intermediate between Proboscina and Idmonea, thus suggesting the 
origin of the family. 
The following is a tabular view of the genera included in the 
family :— 
IDMONIID. 
A. Zoarium encrusting. 
I. Zoarium strap-shaped (like Prodoscina), or if discoid the 
zocecia are arranged on strap-shaped ridges; apertures in 
alternate, pinnately-arranged rows. 
a. Apertures i in single lateral series ‘i .. Ldmonea. 
5. Apertures in double lateral series (except at extreme 
proximal end) . Reptofascigera. 
(Only species, 2. alternata, @ Orbigny, 1853: Pal. 
Frane. Bry. Crét., pl. 744, figs. 4-6.) 
Il. Zoarium discoid (like Berenicea) s “zocecia in radially - i 
arranged rows ue . Phalangella. 
(Only Cretaceous species, Berenicea radians, ‘Novak, 
1877, Bry. Polar Kr. : Denk. Ak. Wiss. Wien., 
vol. xxxvil, pt. 2, pl. iv, figs. 15- Y 
B. Zoarium erect, of hollow branches : se ... Semiclausa. ; 
1 W. D. Lang, ‘‘ A Key to the Published Figures of the Cretaceous Forms of 
Entalophora”’?: Grou. MaG., 1906, p. 462. 
2 Cf. a similar case in the Eleide : see Lang, Grou. Mac., 1906, p. 60. 
3 J. W. Gregory: Brit. Mus. Cat. of Cretaceous Bryozoa, vol. i (1899), p. 150. 
