132 BULLETIN OF THE LABORATORIES 



in outline and separated by thin walls. These walls are most readily 

 detected in weathered specimens, on account of yielding most readily 

 to the dissolving action of the atmosphere. In cross sections 

 tlrey are seen as thin wavy outlines separating the vesiculose 

 tissue of adjacent polyps. On account of the confused structure of 

 this tissue these walls are then seen only on careful examination, but 

 then they are marked enough. The interior of the polyp is filled with 

 vesiculose tissue about the walls without traces of lamellae, next comes 

 a zone in which the vesiculose tissue is combined with radia- 

 ting lamellae, the vesicular tissue itself becomes more regular in 

 arrangement and tends to combine in more or less circular rings 

 around the more central portions of the polyp. Near the centre these 

 rings usually become suddenly indistinct or entirely vanish. In this 

 case they represent the more typical characters of the genus. • In 

 adjacent polyps the variation may be more gradual and then one of 

 the more conspicuous characters of the genus fails. In one of the 

 numerous polyps with this compound structure which may be taken as 

 typical, the diameter of the entire polyp is 9 mm; the diameter as far 

 as the exterior limit of the area of mixed lamellae and vesiculose tissue 

 is 5 mm. The diameter of the last easily seen ring at the interior 

 limit of the vesicular tissue is 2.5 mm. Longitudinal sections show 

 the vertical lamellae towards the centre and the vesicular tissue quite 

 strongly ascending forming on the average an angle of about thirty 

 degrees with the centre of the polyp although this of course is very 

 variable. 



Spongophyllum Sedgivicki, Edwards and Haine in British Fossil 

 Corals, plate 56, figure 2d, is a similar form but smaller. The Austra- 

 lian species is new. A description of the calyces is still necessary 

 before science can be burdened wiih another name. When that is 

 accomplished spongohylloides might not be an inappropriate term. 



PlEURODICTVUM PROBLEMATICUM, GoldfuSS ? 



{Plate XIII, Ftg. 22.) 



Fossils found in the form of casts. Corallum compound, com- 

 posed of polyps intimately united by their walls. The walls are per- 

 forated, the perforations connect the cells of adjacent polyps. The 

 base of the corallum is flat; there being no polyps here to connect the 



