514 DR. HUBRECHT ON A NEW PENNATULID. [May 19, 



septa as we proceed towards the rhachis, a transverse connecting 

 septum, however, keeping up a direct continuity, and being placed 

 perpendicularly to the two parallel ones, and at the same time 

 symmetrically. The internal space is consequently now divided into 

 four spaces instead of tvfo, two lateral spaces having made their 

 appearance in addition to the dorsal and ventral (Plate XXXI. fig 12, 

 and woodcut, p. 515, fig. 2). When we examine the figures in K61- 

 liker's monograph (' Anatomisch-systematische Beschreibung der Al- 

 cyonarien, I. Peunatuliden,' plate x. fig. 78 ; plate xiv. figs. 107-1 13 ; 

 plate xxi. fig. 180; plate xxiii. fig. 212) of sections through the stems 

 of different genera of Pennatulids, we find that there, too, a similar 

 arrangement of the septa and the spaces obtains, and that towards 

 the inferior extremity of the stem the spaces are also reduced to two. 

 One remarkable difference to be noticed in our specimen is this, 

 that whereas in the other Pennatulids au axis of more or less con- 

 siderable size and massive consistency appears and is situated in the 

 median vertical septum above alluded to (r/. Kolliker's figs. 78, 

 108, 110, 212), such an axis is entirely absent in Echinoptilum, no 

 trace of it being found either in the stem, the lower part of the rhachis, 

 or its upper portion. The septum in which it is always developed 

 is there, however, as was just noticed. 



We must now observe that in the rhachis the dorsal, ventral, and 

 lateral spaces which we have been describing for the stem, and which 

 are here so symmetrically placed, are none the less present through- 

 out the whole of the rhachis, but are here reduced in size by the 

 development of spaces exteriorly to tliem, in which the polyps will 

 partly be lodged. Fig. 13 gives a satisfactory representation of this 

 arrangement. It is a section in the lower third of the rhacliis, and 

 shows us the two parallel septa with the perpendicular one between 

 them, situated in the axis of the rhachis, and at the same time the 

 four spaces which they help to enclose, uninterruptedly continued 

 from the stem into the rhachis, their bulk being, however, not incon- 

 siderably reduced. 



At the top of the rhachis they disappear, transverse sections 

 showing that they only reach so far as close to the top, but that at the 

 very extr'^ni^*- —^ly the additional spaces ps belonging to the 

 termii. ^. -^.is are present ; this would to a certain extent 



bring o -., another point of comparison between the septa here dis- 

 cussed and those carrying the axis in other Pennatulids, the latter 

 structure being known not to attain the topmost extremity of the poly- 

 parium, but to stop short close to the top of the rhachis. The accom- 

 panying woodcut (p. 515) exemplifies diagram matically the arrange- 

 ment of the primitive spaces in transverse sections of different regions 

 of the polyparium. For comparison fig. 4 is copied from Kolhker. 



Returuhig now to the base of the stem, we note in longitudinal 

 sections (fig. 9) that here the short median, ventral, and subterminal 

 furrow, already mentioned above when reviewing the external 

 characters of ilie specimen, is indeed a depression in the integument, 

 and that at the bottom of this depression a flat expansion of the 

 sclerenchyma separates the cavities of the hollow stem from the 



