890 PROF. S. J. HICKSON ON THE 



Labiopora group. It is true that the description given by von 

 Marenzeller of the surface of the ccenosteum does not agree with 

 that of the other species of the group, but it does not agree either 

 with the description given of the surface of the ccenosteum of the 

 Errina group. The absence of well-defined coenosteal pores, the 

 grouping of some of the grooved spines in clusters, and the direc- 

 tion of their grooves — all point to the affinities of the species with 

 the Lahiopora group. 



It may be remarked that this is the only species of the group 

 that occurs in deep water. 



Revieiv of the Labiopora Group of Species. 



The careful examination of the specimens belonging to the 

 Lahio])ora group leads me to the conclusion that there are very 

 few characters that can be used with much confidence for the 

 separation of species *. However, it may be convenient for the 

 present to recognise six species : — 



Errina (Labiopora) aspera Linn. Mediterranean tSea. 

 Errina {La'biop>ora) antarctica Gray. Chili and Falkland Islands. 



30 to 45 fathoms. 

 Errina [Lahiopora) moseleyi Ridley. Chili. Shallow water. 

 Errina {Labiopora) novce zelandice Hickson. New Zealand, 



Shallow water. 

 Errina (Labiopora) capensis Hickson. Cape of Good Hope. 



30 fathoms. 

 Errina (Labiopora) gracilis von Marenzeller. Antarctic Sea. 



Deep water. 



Of these six species En'ina (Lahiopora) capensis appeal's to be 

 the most sharply defined. It probably attains to a much larger 

 size, has more robust branches terminating in blunt and some- 

 what flattened extremities. Its substance is coarsely reticular 

 and its surface coarsely granular. The grooved spines are short 

 and semicircular in shape. All the dactylopores are guarded by 

 these spines. 



The other five species are very closely related. Errina (L.) ant- 

 arctica appears to be distinguished from the others by the grooved 

 spines being arranged in definite I'ows, and Errina (L.) moseleyi 

 by the diflerentiation of an anterior from a posterior sui-face 

 of the flabellum. Of Errina (L.) novm zelandicB all that can 

 be said is that it appears to be a very variable species which 

 does not exhibit any one particvilar distinguishing feature. 

 Errina (L.) gracilis is distinguished from the others by the 

 texture of the surface of the ccenosteum, and the colour is not 

 red but white or bi'ownish. Errina (L.) aspera has a close resem- 

 blance to some of the facies of Errina (L.) novce zealandice, but 

 it is always white in colour, in this respect resembling the facies 

 '' Cooki." 



* See Note, p. 894. 



