Simpson — A llevision of the Gorcjonellidae. 265 



anil in fact they are so similar in all species as to be of no spccilic iinpurlance, 

 so that their inchision in each individual description is hardly necessary. 



(b) Motility. — To define the sliape of the verrucae would be to describe the 

 various phases through which it passes from complete expansion to extreme 

 retraction. It may be well, however, to consider some of the phases pre- 

 sented iu the same and different specimens, and note to what extent 

 motility occurs. Fig. 32 of the Cape specimen of Scirpearia Jlcu/dlum and 

 fig. 64 of the type specimen of Scirpearia alba show the verrucae as low 

 cones. Fig. 9a of Juncclla Juncca, and fig. 90«, b, and c of Scirpearvi f%irmta 

 show them as level with the coenenchyma, or even depressed beneath it. 



On the other hand, however, the great majority of the figs. — e.g., 36, 44, 

 85, and 98 — depict them as directed upwards, and adpressed to the 

 coenenchyma. 



When we examine these carefully, we find that the upper surface of the 

 polyp is considerably wrinkled, while the lower is decidedly stretched. (See 

 fig. 49 of the Naples specimen, and fig. 36 of the Cape specimen of 

 8. Jlagcllum.) 



Another phase, however, presents itself. Fig. 2, from a specimen in the 

 Monaco Collection, has been added to show a very peculiar disposition not 

 uncommon in Scirpearia fiagellum. This species is remarkable for the 

 length of its verrucae, the thinness of the coenenchyma, and the consequent 

 slight retraction of the former into the latter. In this figure the verrucae 

 on one side of the stem are all directed upwards, while on the other they 

 are all directed downwards. In other specimens some are directed upwards, 

 some horizontally, and some downwards, while a very peculiar arrangement 

 is seen in the Naples specimen described in this report. The colony has 

 been broken in two and preserved in this state. In the upper part of the 

 colony the polyps are nearly all directed upwards, while in the lower part 

 they are nearly all directed downwards. 



Now it is highly improbable that this state of aifaii'S could have existed 



while the colony was living in the sea ; so that it is not pushing a speculation 



too far to conclude that the position in which the colony was immersed in 



alcohol, for killing and preservation, has determined to some extent the 



direction in which the polyps liave retracted. In fact, the probability is that 



the polyps naturally grow horizontally, but ha\e a power of rotation 



tlu'ough 180° both horizontally and vertically, or, in other words, the oral 



aperture can take up any position on the surface of a hemisphere whose 



radius is the length of the verruca. The mode in which these colonies 



obtain their food, and the .different positions which they must assimie when 



swayed by currents, are stronglj' in favour of such an argument. 



[2 .V 2] 



