. Bulletin of the British Museum (Natural History), Geology. 172 SMITH, PAUL, GALE & DONOVAN forms the flat floor of the sunken petals. This is smooth and forms 37-38% of the petal width at its widest. The petals form an angle of 115° to the anterior and in both specimens there are 33 isopores per column in the anterior petals. The posterior paired petals are shorter than the anterior pair and slightly less sunken. They are 21-24% of the test length in length and in width are 36% of the petal length. The petals extend approximately 50% of the distance to the ambitus. The isopores of the po
. Bulletin of the British Museum (Natural History), Geology. 172 SMITH, PAUL, GALE & DONOVAN forms the flat floor of the sunken petals. This is smooth and forms 37-38% of the petal width at its widest. The petals form an angle of 115° to the anterior and in both specimens there are 33 isopores per column in the anterior petals. The posterior paired petals are shorter than the anterior pair and slightly less sunken. They are 21-24% of the test length in length and in width are 36% of the petal length. The petals extend approximately 50% of the distance to the ambitus. The isopores of the posterior petals are similar to those of the anterior petals and there are 26 or 27 isopores per column. The posterior petals are straight and form an angle to the posterior of about 50°. The perradial interporal zone is smooth and at its widest forms 34-35% of the petal width. Below the petals the pores become widely spaced and minute but remain isopores. The anterior ambulacrum is sunken adapically but by the ambitus it is almost flush. Adapi- cally there are prominent isopores, about 07 mm in width. These have relatively large, oval pores with a narrow, slightly raised interporal partition. There are 13 to 15 such pores, moder- ately widely spaced in each column. Below this the pores become noticeably smaller and further apart. This adapical region extends for about 55-60% of the distance to the ambitus and has a width 33-34% of its length. The floor of the ambulacral groove is largely covered in miliary tubercles, but scattered primary tubercles are also present. Ambulacral pores on the oral surface are small and insignificant isopores except adjacent to the peristome. Here there are large round isopores each with a circular attachment area and a prominent interporal bulge. There are 2 or 3 phyllode pores per column in ambulacrum III, 5 or 6 in ambulacra II and IV and 4 or 5 in ambulacra I and V. The isopores in the subanal region are enlarged in comparison to adjacent isop
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