PENNATULIDA. 63 



differences, will have to be referred, I think, to the species D.gracilc of Verrill. The features in which 

 all the specimens differ from this species are the following: the polyp-calyxes are only here and there 

 seen with a two-lobed edge; and when this is the case it has only arisen by a closing of the mouth 

 of the calyx round the completely retracted polyp 1 ); in other cases - where the contraction of the 

 retractile parts is not so complete - - the abaxial edge of the mouth of the polyp-calyx shows six 

 pointed teeth supported by spicules. Next, the polyps are not placed so close to each other, as given 

 in the description of Verrill and in the figure 1. c. i a; generally, the front edge of a polyp-calyx does 

 not reach farther upward than to the lower end of the calyx placed next above it, and consequently 

 it covers no part of this next calyx; often, especially in the upper part of the rhachis, one polyp is 

 far from reaching to the base of the next With regard to this point, however, it is to be remem- 

 bered that the sarcosoma of the rhachis in all Pennatulids may be shortened by a contraction of its 

 longitudinal musculature, so that the distance between the polyps may be altered; as in Virgularia 

 (i/iirabilis), Stylatula, etc., the appearance of Distichoptilum may also be influenced by this fact. 

 Further, there are found at each polyp, not three but only two zooids (each with a small calyx provided 

 with spicules); they are placed close to the (axial) upper edge of the calyx, one on the dorsal, one on 

 the ventral side of the rhachis, and (very nearly) of the same relative height. When Verrill states 

 that one more zooid is placed in front of i. e. above the calyx, such a zooid is absolutely wanting 

 in all the specimens of the Ingolf; in this respect as in all others these specimens agree with 

 Studer's D. verrillii\ in V err ill's figure also, this third zooid is not seen, and I think its existence 

 quite problematical. Finally, a more or less distinct longitudinal stripe or furrow is found both on 

 the dorsal and on the ventral side of the rhachis; the appearance of this furrow may however, I think, 

 be quite dependent on the degree to which the longitudinal canals are filled, and to the casual contrac- 

 tion of the sarcosoma. The colour is stated by Verrill to be bright orange red, due to the spiciila; 

 end of bulb yellowish >; in the specimens of the In golf* the colour is only red in the upper, abaxial 

 part of the polyp-calyxes, otherwise it is yellowish to yellowish- white; the red colour of the calyxes 

 extends over two only of the lateral points, whilst the other teeth contain colourless spicules (a further 

 reason for overlooking these teeth). In all the features stated, the D, verrillii of Studer agrees with 

 the Ingolf-specimens, except that the calyx is said by Studer also to be provided with two teeth; he 

 declares himself that his species is very closely allied to that of Verrill - - the only differences 

 being the greater distance between the polyps, and the greater size of his specimens -- but these 

 features are of no value as specific characters. So far as I can see, both Stxider's specimens and ours 

 will have to be referred to the species D. gracile first described. 



The calcareous axis is round, in some specimens a little angular or compressed in part of 

 the rhachis. 



In the upper retractile part of the polyps, spicules seem to be wanting, but they are found in 

 the tentacles on the aboral side of the stem, not, however, to the very point; pinnulse are naked. 

 The specimens taken by the ,Ingolf> show the following proportions: 



') VerrilPs fig. I a, which, by the way, is not very detailed, shows only quite retracted polyps. 



