HV \\. \. BKNSON. 381 



space of a centimetre. They are connected by radial pillars, 

 whicli extend pei'pendicularly across all the lamina? making up a 

 latilamina, and may continue even beyond these. These pillars 

 also lie about sixteen in the space of a centimetre. Occasionally, 

 there are Caunopora-tubes, one of which (appearing in figure 8) 

 is about 3 mm. in greatest diameter. A tangential section shows 

 the presence of astrorhizte. 



StromatirporpJIa benaoitl (Plate xxxvii.). — The shape of the 

 ccenosteum cannot at present be stated. The latilaminif are less 

 definitely marked than in the preceding species. The lamina.' 

 are so spaced that about fifty occur in a centimetre, while the 

 radial pillars are also about the same distance apart. They con- 

 tinue across several laminae, at times as many as thirty or forty. 

 The nariow, tabulate, zooidal tubes also continue across as many 

 as ten laminje, but are difficult to distinguish from the ordinary 

 intei'pillar spaces. Small astrorhizse are recognisable in the 

 vertical section. The Caunopora-tubes are abundant, and have 

 a diameter of about 0'5 mm., and show infundibuliform tabulse. 

 This form appears to be similar in some respects to FaraUel(ypora 

 dartinijtonensis (Carter), from the Middle Devonian of Devon- 

 shire. 



Both these forms of HtvomatoporeJla show a more definite net- 

 work, and more continuous radial pillars than the majority of 

 the forms discussed by Nicholson (25). 



The ccenosteum of *S'. loomherensis is unusually large, and its 

 lamina? and pillars are unusually far apart; in S. bensoni, on the 

 other hand, they appear to be closer together than is normal for 

 the genus. In addition to the two forms mentioned, there is a 

 large form apparently belonging to this genus, in which the pre- 

 servation is less perfect. In this, the laminai' and pillar-spacing 

 is farther apart than in the case of S. loombereiisis, there being 

 about ten laminte and nine pillars in the space of a centimetre. 

 The pillars are apparently short. 



Actinostroma aiisfrale (Plate xxxviii.) is characterised by well 

 developed horizontal or slightly wavy laminse, with scarcely 

 noticeable latilamination. The type-specimen is a Hattish frag- 



