VARIATION IN THE 8EPAL8 OF BRUGUIERA 

 RHEEDII BLUME. 



By C. D. Gillies, M.Sc, 

 Biology Department, University of Queensland. 



(With text-figure 10). 



{Read before the Royal Society of Queensland, 24th June, 



1918. 



During the visit to Caloundra in May, 1918, of the 

 Biology students of the University of Queensland, I 

 availed myself of the opportunity for collecting material 

 for the study of the variation in the number of sepals in 

 the calyx of the mangrove, Bruguiera Rheedii Blume. 



The calyx of this form is a conspicuous red structure 

 and is commonly found in the tidal debris along the shores 

 of Pumice-stone Passage, which separates Bribie Island 

 from the mainland. The specimens used in the investi- 

 gation came from this locality and were gathered partly 

 off the plant and partly from the tidal debris. Altogether 

 118 calyces were collected, and it was found that the 

 number of sepals varied from 9 to 13, the frequencies being 

 as follows :— 



No. of sejml.s .. .. 9 10 11 12 13 



Frequency 13 47 38 17 3 



Total number of variatcs : 118. 



The following biometric constants have been calculated 

 from the data given above : — 



Mean: 10.576 + .002. Mode: 10.471. 



Index of variability : .3+. 001. Coefficient of variability : 2.84+. 001. 



One calyx apparently was composed of 10 sepals, 

 including one of abnormal size. On examination it was seen 

 that the latter was formed of two fused sepals, so the calyx 



