HiCKSON — Notes on a Small Collection of Hydrocorallince. 503 



variety of Dlstichopora that I obtained in North Celebes, this irregu- 

 larity in the disposition of the pores was even more pronounced 

 than in the specimens from Australia (PI. xix. fig. 1). In some spots, 

 indeed, the pores are arranged in circles showing a close resem- 

 blance to the arrangement of the pores in Sfylaster and AUopora. 

 There are similar circular arrangements of tlie pores in young 

 specimens from Australia. A careful examination of the soft parts 

 of these specimens leads me to the conclusion that this irregularity 

 in the arrangement of tlie pores is not in itself sufficient to justify 

 the creation of a new species for the Dlstichopora from Celebes, 

 and I am inclined to think that Moseley's species D. irregularis 

 may, after all, be but a younger stage of D. violacea or D. coccinea. 

 In Plate xviii. I have given four water-colour drawings of 

 spirit specimens of D. violacea from Professor Haddon's collection. 

 Fig. 1 represents an adult female colony with ripe ampullae. The 

 colour is deep violet in the basal and older parts, with a tendency 

 to become reddish in the region of the ampullae, and fading off 

 into a pale yellowish tint at the free extremities of the branches. 

 The shape of the colony is irregularly flabelliform. This shape 

 does not seem to be produced by the branching of the colony 

 taking place in only one plane, but by the feeble development of 

 the branches that originate in any other plane than that of the 

 flabellum. An examination of young colonies and the extremities 

 of older ones proves most conclusively that the growth in com- 

 plexity is produced by dichotomy of the terminal branches and the 

 subsequent suppression of those branchlets that are not situated 

 in the plane of the flabellum. The rows of pores situated irregu- 

 larly on the flabellar surfaces such as may be seen in all the 

 figures given, I consider to represent branches that have been thus 

 suppressed. To return to fig. 1. On both sides of this specimen 

 there are dense clusters of female ampullae situated on the 

 secondary branches, that is to say, there are no ampuUse on the 

 terminal pale branchlets nor on the thick basal trunks. They are 

 found only on the branches between the two extremities. In old 

 colonies, such as the one I am now describing, ampullae are found 

 on both sides of the flabellum, in younger ones they occur on one 

 side only. The female ampullae may be readily distinguished 

 from the male by the fact that they stand out on the surface as 

 rounded prominences, marked at their edges by radially arranged 



