834 MR. A. W. WATERS ON 
forms, but evidently this is a long way back, so that now 
articulation is apparently a generic character; but there must 
have been a time when closely related forms were in some cases 
continuous, in others articulated, but now both zoarial and 
zocecial characters indicate a group of Catenicellide. In Cellaridz 
and Thalamoporella the articulation is more recent, and should 
not be made a generic character. 
Examining the Cyclostomata in the same way, we find to a 
certain extent parallels with the Cheilostomata : Diastopora, or 
perhaps we should say Diastoporide, occurs adnate, but also 
bilaminate in such forms as D. intricaria, Mesenteripora; and 
some forms now placed with Hntalophora, such as H. regularis 
MacG., belong to this family. Even the D. obelia division, which 
it has been proposed to raise to a genus Diplopora*, has adnate 
forms, as well as the erect fossil Diastopora brendolensis Waters 7, 
with tubules between the zoecia. A Stomatopora-like growth 
may become erect, and too much importance has been attached 
to whether a form is adnate or erect. There are adnate forms 
with Heteroporidan structure, and some bilaminate as Pavospirua. 
The ovicells together with the oceciostomes ete. are, as stated, 
going to assist us to trace relationship, but to what extent we 
cannot yet say, as our knowledge is in most families very in- 
complete, often fragmentary or absent. However, although only 
sufficient to show the direction in which work is wanted, it may 
be useful to put together what I have gathered from my own 
collection and from published accounts of recent forms. 
In Crisiaz the ovicells of most species are known, and they with 
the oceciostomes furnish most useful characters in determination. 
In the species examined there are 8—9 tentacles. 
In /dmonea, as at present understood, there are some important 
and rather puzzling differences in the ovicells. There is, Firsv, 
the /. radians, mentioned in this paper, also /. atlantica Forbes, 
I. concava Reuss, and J. parasitica Busk, in which the oeeciostome 
occurs on one side, usually on the second of the series enveloped 
by the ovicell, and by the first or second zoewcium counting from 
the median line; the tube curves over and turms downwards 
(PI. IT. fig. 6, @.). In these the ovicell spreads across the anterior 
surface. 
Seconp. There may be merely an anterior inflation, usually 
near to a bifureation, with a central ocwciostome, as /. interjuncta 
MacG. 
TurrD. I have a fragment of an /dmonea, probably australis 
* This name cannot stand as it has already been used, see page 836. 
+ Quart. Journ. Geol. Soc. vol. xlviti, p. 155, pl. iii, fig. 1 (1892). 
~ Reuss (Foss. Polyparien des Wiener Tert. p. 99) described the Cyclostomatous 
ovicells as Caelophyma, of which C. glabrum occurred on Crisia hérnesi (a Crisia), 
Retepora disticha (apparently Idmonea), and R. cancellata (do. Idm.); and 
Celophyma striatum on Hornera hippolithus. i 
Hagenow (Bry. Maest. p. 105) described Calophyma levis on Truncatula repens 
and T. truncata; C. constrictum on Idmonea tetrasticha (this is not Idmonea, 
perhaps a worn Truneatula); and C. granulatwn on Idm. lichenoides. Gregory 
does not quote Hagenow quite correctly. 
