502 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



Measurements of branches of Porites touiai. 



Specimen No. 



Length. 



Diameter of 

 lower end. 



Diameter of 

 upper end. 



1 



mm. 

 40.5 

 46 



74 



mm. 

 7 by 8 

 13. 5 by 14 

 11 by 17 



mm. 



6. 75 by 7. 5 



12 by 14 



8 by 10. 5 



2 



3 





Specimen No. 3 lias been somewhat compressed by pressure. 



Calices shallow, diameter about 1.75 mm., a few large calices have 

 a greater diameter of as much as 2.5 mm. There is a pronounced 

 tendency for the calices to occur in rather short, longitudinal series. 

 One series is 5.5 mm. long and contains 4 calices, one of which is 

 immature; another series, which is slightly curved, is 7.5 mm. long 

 and contains 5 calices. The calices within a series are separated by 

 indistinct walls ; in fact, between some no definite wall is recogniz- 

 able, the distal ends of septa from one calicinal center being continu- 

 ous with the distal ends of the septa belonging to the next center! 

 Such series are formed by fission. The walls between adjacent series 

 are definite; a wall-ridge is usually but not invariably recognizable, 

 it is interrupted and straight or somewhat zigzag. There is in places 

 a considerable development of intercalicular or interserial reticulum, 

 in which the radial (costal) skeletal elements are conspicuous. 



The septal arrangement is irregular as would be expected in a coral 

 in which asexual reproduction is largely by fission. Groups of calices 

 from two specimens are shown on plate 150, figures la, 4. The 

 scheme where complete seems to be a solitary directive, two lateral 

 pairs on each side of the plane of symmetry, and a ventral triplet in 

 which the inner ends of the lateral members converge toward the 

 included directive and join it by synapticulae, but such a schematic 

 arrangement is rarely recognizable. There are usually from 10 to 14 

 septa fusing in pairs or in threes, with a solitary septum, the directive 

 plane being indicated in many calices by an elongate septum, to the 

 inner end of which the columellar tubercle may be attached. Usually 

 coarse septal granules slightly detached from the wall form a ring, 

 and the pali form a ring surrounding the columellar tangle. There 

 is indefiniteness and irregularity in the pali as there is in the septa; 

 the normal number seems to be five or six. There are an outer ring 

 of synapticulae, more or less fused to or detached from the wall, and 

 an inner palar ring. 



There is a well developed, rather prominent columellar tubercle, 

 which is joined by radii to the inner ends of the septa. 



Locality and geologic occurrence. — Canal Zone, station 6016, quarry 

 in the Emperador limestone, Empire, collected by T. W. Vaughan 

 and D. F. MacDonald. 



Type.— Cat. No. 325105a, U.S.N.M. pi. 150, figs. 1, la. 



Paratypes. — Cat. No. 3251055, U.S.N.M. (3 specimens). 



