HYDROCORALLTNE GENUS EURINA. 879 



Taking these characters as giiides it seemed to me that the 

 diagnostic characters of the three genera might be stated as 

 follows : — 



(a) Coenosteum hard and compact, perforated by well- 



defined coenosteal pores. Grooved spines turned 

 towards the apex of the branch. 



1, With short grooved spines and only one kind of 



dactylopore Errina. 



2. With long grooved spines and two kinds of 



dactylopores Spinipora. 



(b) Coenosteum gi'anular and reticulate, Avithout well- 



defined Cfjenosteal pores. Grooved spines turned 

 away from the apex of the branches or irregularly 

 placed Lahiojjora. 



If the three genera be joined together to form a subfamily, the 

 Errinina, this subfamily might be defined as follows : — ■ 



Hj'drophytum arborescent and irregularly flabelliform, gastero- 

 pores and dactylopores not arranged in cyclosystems. Gastero- 

 pores with a large brush-like style. Dactylopores without a 

 style. Some of the dactylopores protected by a grooved spine 

 (narial process) on the surface of the coenosteum. 



This arrangement of the genera, however, breaks down on 

 further analysis, and I see no other course than to arrange all the 

 species in three groups under the one generic name Errina. 



The genus Errina was founded by Gray in 1835 for a species 

 of coral found in the Mediterranean Sea and formerly called 

 Millepora aspera by Linnaeus. 



As von Marenzeller has pointed out, Gray's description of the 

 spines in this species as *' Superne longitudinaliter fissee " is not 

 consistent with the description of the species known to Linnaeus 

 and Esper. 



I have examined the type specimens in the British Museum, 

 and have found that Gray's description is not correct. The 

 spines in these specimens are irregular in arrangement, but where 

 they are isolated and not in clusters the groove is directed away 

 from the apex. Moreover, the character of the surface of the 

 coenosteum, the presence of a few small dactylopores without 

 grooved spines, and other features prove that this species is more 

 closely related to the type species of Labiopora than it is to any 

 of the other species of Errina. 



Accoi-ding to the system I had, at first, proposed the tj^pe 

 species of Errina would thus be a species of Labiopora and 

 Moseley's Errina ramosa would become the type species of the 

 genus. 



Such a proposal, therefore, would not only be contrary to the 

 rule of zoological nomenclatvire, but it would also be extremely 

 inconvenient. Moreover, one species at least [E. macroyastra) 

 would occupy an intermediate position, having a surface similar 



