HYDROCORALLI>rE GENUS ERRIXA. 887 



The hydropliytum is pi^obably flabellate in growth, the ramifi- 

 cation not very profuse and anastomoses rare. 



Colour : salmon-pink. 



Surface coarsely granular and substance coarsely i-eticulate. 



As this species seems to approach the Errina group in some 

 respects, a.ttention may be called to the striking difference there 

 is between the coarsely granular character of its surface and the 

 fine smooth porcellanous character of the surface of the Errina 

 group. 



Grooved spines very short, numerous, quite irregular in arrange- 

 ment and never in clusters. The form of the spine is that of a 

 shallow semicircular ridge open on the side turned away from the 

 apex. 



Gasteropores equally distributed on both sides of the branches, 

 never provided with a lip. Diameter 0"3 mm. 



Large dactylopores about 0*25 mm. in diameter. 



Small dactylopores :— It may be open to discussion whether 

 there is or is not any true dimorphism of the dactylopores in this 

 species. It has been shown that in one of the specimens from 

 New Zealand (" Dendyi ") the small dactylopores are provided 

 with shallow collars. In the Cape specimen some of the dactylo- 

 pores are considerably less in diameter than the majority, but 

 they are provided with exactly the same kind of semicircular 

 ridge as the larger ones. The question of dimorphism, therefore, 

 resolves itself in this case into a question whether the essential 

 feature of the dimorphism of the dactylopores consists in their 

 size or in the presence of a grooved spine. Ridley states that in 

 Errina {Labiopora) moseleyi the dactylopores a,re of the usual 

 uniform size, and the two kinds can only be distinguished by the 

 presence or absence of nariform processes. These facts seem to 

 emphasize the conclusion that the so-called dimorphism of the 

 dactylopores is not really a feature of very great importance, and 

 to suggest as a probability that the small dactylopores are the 

 shelters for young dactylozooids which in their later stages of 

 growth increase in size and become protected by a grooved spine. 

 The specimen described and figured by Gray (1872) as Errina 

 fissurata, from the Antarctic seas, was apparently very closely 

 related to this species. Unfortunately the specimen has been 

 mislaid {fide Moseley) and cannot therefore be re-examined, but 

 the figures show a similar robust habit of growth and short semi- 

 cii"cular grooved spines with the grooves all turned away from the 

 apex of the branch. 



Errina (Labiopora) Antarctica Gray. 



Porella anta?xtica Gray. 



Labiopora antarctica Moseley. 



Labiopora antarctica Ridley. 



The type-specimen was found off the Falkland Islands, 

 54° 27' S., 59^ 40' W., in 45 fathoms. 



A second specimen, attributed to this species by Ridley, was 

 found in Trinidad Channel, S.W. Chili, in 30 fathoms. 



59* 



