127 



quarter as thick as in the last species. There is no sphincter 

 muscle and the tentacles are introversible from the bone. 



There are such a number of mesenteries (62 in one specimen) 

 that the highest septa in each system are exocoelic. There are 

 24 mesenteries reaching the stomodoeum, which has a similar 

 number of ridges over their attachments, passing below into 

 their filaments. The nematocysts are arranged in the latter as 

 in the last species, but are quite well-developed. 



The endoderm is similar to the last species. No definite 

 nematocysts exist, but there are a number of granular, oval 

 masses in patches on the septa sides, which appear to represent 

 them in a still further reduced state. Boring algae are not 

 present. 



5. DUNCANIA CAPENSIS. 



The polyp is seated on the cup, and does not extend in any 

 way outside its wall. When expanded, it evidently stands up for 

 some considerable distance above its wall, but in contraction this 

 part is by means of a few sphincter muscular fibres drawn over 

 the peristome and tentacles. These latter number 12, the 

 bases of each of which are crossed by a pair of mesenteries. 

 Underneath their epithelium the structureless lamella is rela- 

 tively thick and rather vacuolated, and in correspondence the 

 tentacles only appear to be introversible at their bases. 



The single specimen examined has 68 mesenteries, 12 pairs 

 on either side of septa I. and II., equal in size and alone joined 

 to the stomodoeum, which is thickened over their attachments 

 for the whole of its length, 12 pairs on either side of septa III. 

 and 10 pairs enclosing the 10 septa of cycle IV. ; the septa hence 

 are all entocoelic. Filaments occur on all except one rather 

 rudimentary pair of cycle IV. The lower ends of all are much 

 convoluted, forming acontia, and crowded with nematocysts of 

 the usual type. 



The endoderm and testes are the same as in other species, 

 but the former has no nematocysts. The testes are formed by 

 a single thickness of follicles, and are situated behind and above 

 the acontia They occur in the mesenteries of cycles I., II. and 

 III., but only on the largest of the latter. This distribution may 

 be due to age — the coral was only 1 1 " 5 mm. across the calicle — 

 but some of the mesenteries of cycle IV. are larger than those 

 of III., which have testes, and it seems not improbable that the 

 mesenteries of cycle IV. never have any generative organs. 



