328 SIDNEY F. HARMER. 



find no indication of a double calcareous wall in tliis species, 

 and it therefore appears to me that the frontal wall is in a 

 Lepralioid condition, the inner calcareous wall alone being 

 developed, and being perforated by a series of vacuities, 

 while the outer wall remains membranous. The probability 

 that a layer of living tissue (epitheca) overlies the calcareous 

 wall is increased by the fact that the surface of the latter is 

 ridged, a condition which is usually associated with a covering 

 of living tissue. 



The lateral junctions of the frontal bars are indicated by 

 prominent radial ridges, each of which rises to a small tubercle 

 just inside the line of the membranous papillas above described. 

 The pores consequently lie, as described by other observers, 

 in radiating furrows. That the union between the bars has 

 not been complete is indicated by the fact that a thin line of 

 air in some cases underlies the ridge. 



The consideration of these facts suggests that the frontal 

 wall has here not been formed by the overarching of the 

 main spines, but by the development of the inner lobes of 

 branched spines. It is impossible not to be reminded of the 

 condition described by Jullien (1886, p. 609) in the 

 Cretaceous Steginoporidte, where a calcareous wall ^ is 

 formed by the growth of branched peristomial spines. 



I have, unfortunately, been unable to make out the con- 

 dition of the compensation-sac in C. radiat;i, but it is well 

 known that this species may possess a well-marked median 

 pore (m. p.). In addition to this Microporelloid feature, it may 

 be noticed that the zooccium is surrounded by a flat basal lobe 

 formed of pore-chambers," as in Microporella ciliata and 

 M. malusii. These are not present in C. philomela. 



There can, I think, be little doubt that C. radiata cannot 

 be retained in the same genus with C philomela, and it is 

 possible that its affinities are rather with the Microporellida;. 



Cribrilina figularis, Johnst. (Plymouth), is another 

 species in which, so far as can be judged from dry material, 



' Wliicli, however, would not appear to correspond with that of C. radiata. 

 ' The details of the pore-chambers are not indicated in (ig. 7- 



