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 by 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 ihave intertered with the septal dis- 

 tribution. 



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

 symmetrical 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 secondare' 

 septum. There are six systems of septa in the bud, and in four 

 there is a secondary septum ; two of tliem are long and two sliort. 

 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 tiiird and fourth 

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

 The fifth system has a long secondary and a tertiarj', 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 aliort or be rudimentary, so that there are three successive septa 

 eqtial 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 

 ))rimaries 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 there is along septum 

 occupying the position of the fifth order between each tertiary and 

 tlie 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 arranse- 

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

 alternate. 



