1H83.] MADREPORARIAN GENUS PHYMASTR.EA. 411 



There is considerable distance between the corallites at the surfpce, 

 amounting to 1 millim. and more, and this is crossed Ijy the junction- 

 processes. These are very variable in their size and distribution ; 

 some do not reach across, and others are constricted in the middle. 

 Very broad ones are exceptional. 



The irregular shape of the corallites and calices is due to pressure 

 during growth and the pushing upwards of growing buds ; and this 

 irregularity of outline appears to have interfered with the septal dis- 

 tribution. 



In a very small calice belonging to a small bud, which is nearly 

 S3'mmetrical and circular in outline, there are six primaries; but where 

 a little pressure has produced flattening, one of the primaries is 

 smaller than the others and might be mistaken for a secondary 

 septum. There are six systems of septa in the l)ud, and in four 

 there is a secondary septum ; two of them are long and two short. 

 In the other two systems, near the flat part, there are no secon- 

 daries. 



A second bud, which is oval elliptical in outline, being compressed 

 from side to side, has six primaries, and where the pressure was at 

 one end the primary there is small. There are, as usual, six systems. 

 In the first, commencing to the right of a primary in the long axis 

 of the calice, there is a secondary which is long, and in the second 

 the secondary is a mere rudiment. In the third system the secondary 

 is rudimentary, and so it is in the fourth ; so that the tliird and fourth 

 systems, with the intermediate small primary, look like one system. 

 The fifth system has a long secondary and a tertiary, small and 

 rudimentary, on either side ; and the sixth system is like the second. 



In the larger calices the secondaries equal the primaries, and 

 some tertiaries do the same ; moreover, in the same system a tertiary 

 may al)ort or be rudimentar}\ so that there are three successive septa 

 equal in length, i. e. a primary, a tertiary, and the secondary, and 

 then comes a small tertiary. In the same calice in the next system, 

 the normal long secondary has short tertiaries on either side ; but 

 the next system has a secondary equal in length to the primaries ; on 

 one side of it is a small tertiary, and on the other a long tertiary with 

 a small septum between it and the secondary. This is a very irre- 

 gular and abnormal distribution. In the next system the secondary 

 is small and the tertiaries are as large as primaries, and between the 

 jirimaries and the tertiaries is a rudimentary septum. None are 

 found on either side of this secondary septum. The irregularity 

 of the septal distribution in the last system of all transcends any 

 thing I have ever seen. The secondary and the two tertiaries 

 are equal in size and resemble primaries; and (here is along septum 

 occupying the position of the fifth order between each tertiary and 

 the secondary. Between one primary and the tertiary there is a 

 septum of the fourth order, and between the other primary (the first in 

 the calice) and the tertiary there are two septa ! In the largest 

 calices the septal arrangement appears to be without definite arrano-e- 

 ment in cycles and systems, and large and much smaller septa 

 alternate. 



