دی سے 
_centric structure of this kind; his genotype Calathium 
"formosum is a simple conical cup with very large 
- outer pores (over 1 mm.), regularly arranged in a. 
diamond pattern. 
The specimen here illustrated is 
evidently related to our Metaldetimorpha and not to 
the genotype of Calathium. 
DI UG polymorpha. 
In Bornemann’s 1886 monograph a description and 
"photographs are given of his genotype Protopharetra 
` polymorpha; 
-roughly in our Plate LII, Fig. 211. 
the following, remarks: 
fibre tissue zones of densely packed fibres which then in 
one of these photograhs is sketched 
Bornemann makes 
*Often there appear within the 
‘cross section appear as a concentric closed ring, but in 
longitudinal section and oblique section give a very 
— irregular picture of the structure, because one part shows 
cross sections of distant fibres, another part the fibres 
Wi 
united to a porous wall, in which only small round 
‘lumina remain open." 
. This description has some 
resemblance to ours of Metaldetimorpha yorkei, (see our 
Plate XXXI, Fig. 
. Bornemann also says, 
` sometimes tubular root fibres, consisting of a simple 
127 and Plate XLI, Fig. 159). 
*On the outer wall one observes 
wall which in cross section appear as rings or ellipses." 
- But Bornemann also says that his specimens have mostly 
.a central tubular cavity, which is separated from the 
surrounding tissue by a delicate sieve-like porous wall 
formed by union of the fibres. 
more than one species is 
It is possible that 
included in Bornemann’s 
material, one a Protopharetra with inner wall, the other 
morpha. 
an irregular or parasitic growth allied to Metaldeti- . 
Some of these apparently parasitic forms of the order 
` Grommyocyathina may be placed in a new family 
"Exocyathidae, with Exocyathus as the typical genus. 
Labyrinthomorpha was 
family Vesiculoidae. 
a 
placed by Vologdin in a 
CLASSIFIED LIST OF GENERA. 
The following list of genera of the Pleospongia is 
poate provisionally o on the foregoing lines: 1 
Class PLEOSPONGIA, Okulitch. 
Order MONOCYATHINA, Okulitch. 
Family Monocyathidae, Bedford. 
Monocyathus, Bedford. 
? Tunkia, Bedford. ۹ 
Family Rhabdocyathidae, Vologdin. 
_Rhabdocnema, Okulitch. 
Rhabdocyathella, Vologdin. 
Yakovlevia, Vologdin. 
3 Family Archaeophyllidae, Vologdin. 
EAA QUT Yologdin. 
| 
Butovia, Vologdin. 
Family Rhizacyathidae, Bedford. 
Rhizacyathus, Bedford. 
Order ACANTHINOCYATHINA, Okulitch. 
Family Acanthinocyathidae, Bedford. 
Acanthinocyathus, Bedford. 
Pinacocyathus, Bedford. 
Order AJACICYATHINA, Bedford. 
Family Alphacyathidae, Bedford; 
Alphacyathus, Bedford. 
Coelocyathus, Vologdin. 
Dictyocyathus, urtar 
Dokidocyathus, Taylor. 
Spirillicyathus, Bedford. : 
Family Ajacicyathidae, Bedford. 
Ajacicyathus, Bedford. 
Archaeocyathellus, Ford. 
Cadniacyathus, Bedford. 
Densocyathus, Vologdin. 
_Formosocyathus, Vologdin. 
Leptocyathus, Vologdin. 
Orbicyathus, Vologdin. 
Protocyathus, Ford. 
Polycyathus, Vologdin. 
Sajanocyathus, Vologdin. 
.Septocyathus, Vologdin. 
Somphocyathus, Taylor 
Tumulocyathus, Vologdin. 
Ventriculocyathus, Vologdin. 
Zonacyathus, Bedford. 
JA 
Family Bronchocyathidae, Bedford. 
; Bronchocyathus, Bedford. 
Clathrocyathus, Vologdin. 
Cyclocyathus, Vologdin. 
Ethmocyathus, Bedford. 
Tercyathus, Vologdin. 
Family Coscinocyathidae, Taylor. 
Coscinocyathus, Bornemann. 
Coscinocyathellus, Vologdin. 
Coscinoptycha, Taylor. 
Polycoscinus, Bedford. ` 
Tuvacyathus, Vologdin. 
Family Sigmocoscinidae, Bedford. 
Sigmocoscinus, Bedford. 
Carinocyathus, Vologdin. 
Family Putapacyathidae, Bedford. 
Putapacyathus, Bedford. 
The following genus is of doubtful affinity. 
Gareth Billings. 
L. Order METACYATHINA, Bedford. 
Family Metacyathidae, Bedford. 
Altaicyathus, Vologdin. - 
1 
