STYLASTERIDAE (HYDROCORALS) FROM SOUTHERN SEAS 37 



between the spines. In the terminal branches all intermediate stages occur (see Broch, 1942, p. 44), 

 and von Marenzeller (1903) was accordingly inclined to consider the small pores only as developmental 

 stages of the larger pores of the spines. It is impossible from examination of dried specimens alone to 

 solve this question or to determine whether a real dimorphism exists. But investigation of the soft 

 parts shows that the dactylozooids also exhibit a dimorphic development correlated with the type of 

 pore. The dactylozooids inhabiting the simple pores of the coenosteum are digitiform (Fig. 1) and 

 lack a specially developed basal adhesive part attached to the bottom or wall of the pore. The dactylo- 

 zooids of the ' large pores ', or grooves of the spines on the other hand, have a long basal segment 

 attached to the wall of the lower part of the groove and the outer 

 part of the adjoining pore, the digitiform, free part of the dactylo- 

 zooid arising from the middle of the basal segment (Fig. 2). In 

 the Discovery specimens the contracted free part is shorter than 

 the basal segment, and it is impossible to judge of its length 

 when extended. We must, however, presume that its powers of 

 extension are rather large. 



Thus it appears that a real dimorphism exists among the 

 dactylozooids of E. antarctica correlated with the dimorphic 2 



development of the dactylopores. _,. _ „ , 



r . - rigs. 1, 2. Ernna antarctica from bt. 652. 



The male ampullae contain a tew gonophores (generally three) (^ simple, digitiform dactylozooid from 



in different stages of development. When one gonophore is quite P ore between the spines. (2) Dactylozooid 

 11 1 • j\ from the groove of a-spme; the digitiform, 



ripe and about to discharge its contents, the smallest (third) f ree part of the zooid (z) arises from the 

 gonophore is only a rudimentary bud. No blastostyle can be middle of a large, adhesive basal part (/;). 

 detected in the ampulla. In this respect E. antarctica obviously 



differs from E. spongiosa Broch, 1942. The spadix of the male gonophore varies somewhat in shape, 

 but always seems to be branched. In some cases it forms a very primitive 'trophodisc', whereas 

 in other cases it is bi- or trifurcate, with the branchlets embedded in the contents of the gonophore. 



The female ampulla only contains one gonophore. In those ampullae which were either empty or 

 contained planula larvae about to escape, no secondary gonophores were seen. This may of course be 

 a chance observation. The ripe ovum rests on a slightly hollowed bowl-shaped trophodisc, which in 

 structure is intermediate between the trophodiscs of Stylaster roseus and S. gemmascens (Broch, 1942). 



It is evident from the general characteristics of the colonies and the coenosteum that Errina gracilis 

 (von Marenzeller, 1903) is a synonym of E. antarctica, and there is no reason to distinguish a form 

 kerguelensis (Broch, 1942) as distinct from the typical form of the species. 



Errinopsis reticulum n.gen., n.sp. 

 (PI. II, fig. 2; PI. Ill, figs. 1, 2) 

 St. WS 246. South of Falkland Is., 52 25' S, 6i° 00' W, 208-267 m. Coarse green sand and pebbles. 



The Discovery material consists of four colonies, luxuriant but not quite intact, and several 

 fragments (probably broken away from the peripheral parts of the colonies). The largest colony, 

 a splendid specimen with the greater transverse diameter measuring 32 cm. and a height of 25 cm. 

 (the basal part with the attachment to a support has been broken away) is dried, consequently the two 

 colonies next in size, one male and one female, which have been preserved in alcohol, have been 

 selected as type specimens. They are reproduced in PI. II, fig. 2, and PI. Ill, fig. 1. 



As indicated by the specific name reticulum, the colonies throughout have the appearance of a simple 

 or complex fan, built up of a coarse network or filigree of anastomosing branches. Along the periphery 



