62 PENNATULIDA. 



much more numerous, the retractile parts of the polyps very dark-coloured, the spicules more slender 

 and fewer, especially on the peduncle. Although several of these differences are of such a nature, 

 that in some other Pennatulid-genera they would not be regarded as specific differences, I dare not 

 overlook them with regard to the genus Protoptihim, our knowledge of the variation and the change 

 in growth of this genus being still very incomplete. Accordingly I take - for the present - Pr. 

 smittii to be a young stage of another species than my Pr. denticulatum. They belong both of them 

 to the Atlantic Ocean, and the great distance between the localities, respectively ca. 36 N. Lat. 14 W. 

 Long, (the Josephine Bank), and ca. 58 N. Lat. 40 W. Long., need not in itself - - any more than the 

 difference in depth (228 1695 fathoms) -- prove any specific difference, as may be seen from other 

 cases (e. g. Anthoptilum grandiflorum a. o.). 



Distichoptilum Verrill. 



The genus has been established by Verrill on one specimen of the species mentioned below, 

 and characterized in the following way: Slender pennatulids, with an axis through the whole length. 

 Polyps arranged alternately, in a simple row, on each side. Calicles bilobed, appressed. Zooids three 

 to each polyp, one in front and one on each side of each cell. Spicula abundant in the calicles, 

 rachis, and stalk; those in the stalk are small, oblong, triquetral, interwoven. In this diagnosis, 

 however, the following alterations have to be made: the calyxes of the lateral polyps are provided 

 with several (6) teeth on the abaxial edge; the axial edge is toothless, and the axial side of the calyx 

 fuses with the rhachis. The number of zooids is two at each polyp; they are placed directly above 

 the mouth of the calyx of the polyp, one on the dorsal side of the rhachis, and one on its ventral 

 side. The peduncle increases evenly in thickness downwards. This genus is especially interesting 

 in that it retains as a constant feature, an arrangement of the polyps which in other Pennatulids is 

 only found as a transitory one in young stages, and which may really be more or less distinctly 

 traced in all the Pennatulids of which we know sufficiently young stages; it is seen most distinctly 

 in the Protocauton-stage of the Virgularise and in Protoptilum. This simple arrangement in Disti- 

 choptilum is not only a constant feature, but persists throughout with the utmost regularity, which 

 gives to the whole colony an exceedingly emphatic character of simplicity. 



Distichoptilum gracile Verr. 



(PL I, Figs. 12, 13, 14). 



Distichoptilum gracile Verrill. Am. Journ. of Sc. 24, 1882, p. 362, Note. 



Bull. Mus. Comp. Zool. Harvard Coll. Vol. XI, Nr. i, 1883, p. 8, PI. I, Fig. i. 

 Verrillii Studer. Ibid. Vol. 25, Nr. 5, 1894, p. 59. 



At two stations, very far from each other, one in the Davis Straits, the other south of 

 Iceland, the Ingolf has obtained several specimens of a Distichoptilum which, in spite of some 



