1885.] DR. HUBRECHT ON A NEW PKNNATUHD. 517 



noptilum are, however, less regularly arranged in distinct rows, the 

 ventral surface is not in the same way wholly devoid of polyps &c. 

 This is another reason for assigning a not unimportant intermediate 

 position to the new genus. 



Echinoptilum will best be placed in Kolliker's section Spicatse, 

 subsection Junciformes (/. c. ' Challenger ' Reports), and in that sub- 

 section it must form a new family, that of the Echinoptilidse, charac- 

 terized by the important fact of the total absence of anything 

 resembling an a?:is, present in all other Pennatulidae with the 

 exception of certain species of the most primitive section, the 

 Veretillese. In the very divergent section of the Renillese also an 

 axis is absent. 



The fact that certain species of Veretillum and of Cavernularia 

 (another Veretillid) have an axis, whereas others of the same genus 

 have not, is no argument to disqualify the new family ; as it must be 

 borne in mind that this degree of variability is only exhibited by 

 species of the most primitive section of the Pennatulids, in which the 

 axis may well be said to make its first appearance, being insignificant 

 and of variable dimensions in Veretillum cynomorium, Cavernularia 

 glans, and Cavernularia lutkeni. Its total absence in the RenillesB 

 also tends to prove that in the original stock from which the Penna- 

 tulids have sprung an axis was absent. This section is characterized 

 by Kolhker {I. c. ' Monographic der Alcyonarien,' 1872, p. 263) as 

 " very different from the other Pennatulids in its possession of a more 

 simple internal structure," and related to the lowest Veretillidse. It is 

 thus the more remarkable to find an axis to be totally deficient in 

 the new genus, which already so clearly shows points of agreement 

 with those groups that are generally recognized as more highly deve- 

 loped, and in which an axis is present — sometimes even very strong 

 and massive — without a single exception. 



EXPLANATION OF THE PLATES. 

 Plate XXX. 



Fig. L First specimen oi EcUnoptihom macintoshii, lateral view, enlarged about 

 \\ times : I, rhacbis ; s, stem. 

 2 & 3. Second specimen of the same, seen from below (2) and in lateral 

 perspective (3), enlarged \\ times: r, rhachis; s, stem. 



In fig. 1 the median ventral depression at the lower extremity of 

 the stem is visible ; in figs. 2 and 3 the median ventral furrow on the 

 rhachis. 



4. Front yiew of a polyp-cell and its calcareous spicules, more considerably 



enlarged. 



5. Lateral view of the same. The polyp represented as emerging from the 



cell is entirely imaginary, and only meant to indicate the position of 

 the opening in the cell. 



6. Dorsal, and Fig. 7 ventral, view of the rhachis of specimen fig. 1, exactly 



reproducing the position of polyp-cells and zooids on these two sur- 

 faces. The ventral furrow on the lower part of the rhachis is plainly 

 visible in fig. 7. 

 8. Part of a transverse section, intended to show the perforation of the 

 wall of the polyparium z, corresponding to a zooid. d I, the longitu- 

 dinal dorsal channel ; sp, spicules in the integument. 

 Proc. Zool. Soc— 1885, No. XXXIV. ,34 



