504 Scientific Proceedings, Royal Dublin Society. 



shallow ridges of the coenosteum which give the whole ampulla a 

 stellate appearance when examined with a simple lens. 



The male colonies (fig. 3) I have examined have been usually 

 smaller in size than the female, and of a brownish colour, frequently 

 with a dash of purple in it. The male gonads may be clearly seen 

 from the surface in spirit specimens as small pale oval bodies, 

 sometimes solitary, sometimes arranged in groups of three or four 

 together, the groups and solitary gonads together forming a 

 cluster situated usually on one side only of a secondary branch. 

 In the figure the gonadial area contains about thirty of the groups 

 and solitary gonads. The gonadial area is paler in colour than 

 the rest of the branch, but is not raised above its general surface, 

 so that in dried specimens the male ampullee cannot be seen from 

 the surface. When the young embryos of Distichopora escape 

 they leave a considerable scar on the surface, but this is almost 

 immediately replaced by the growth of a thin layer of coenosteum 

 to protect the new ovum that is developing in tlie ampulla vacated 

 by the embryo. In spirit specimens the scars are but rarely seen. 

 In dried specimens, however, the thin layer of coenosteum readily 

 breaks down, and consequently we find on the old Distichoporas 

 in museums numerous large gaping scars. 



The spermatozoa, on the other hand, are discharged by a 

 narrow seminal duct — vas deferens — and consequently no con- 

 spicuous scar is formed at any time on the male colonies by the 

 discharge of the contents of the ampulla. 



A few very small bright yellow (fig. 4) colonies were found in 

 Professor Haddon's collection. On only one of these were any 

 ampullae to be seen — a group of four or five female ampullae — the 

 others were quite immature. No trace of ova or spermcells were 

 to be found in a series of sections. 



The position of the gastropores and dactylopores in the colony 

 was correctly given by Moseley, and I cannot do better than 

 quote his words : " Pores very deep, prolonged in curved lines 

 side by side in the plane of the flabellum, inwards and downwards 

 towards the bases of the branches, forming thus throughout the 

 tiabellum a thin, continuous tract of fragile tubulate tissue in 

 which the successively developed curved pore-tubes stand out fan- 

 wise, separating from one another the compact masses of coenenchym 

 forming the opposite faces of the branches." 



