3 2 PENNATULIDA. 



right down on the upper portion of the bulbous part; in the narrow part of the stalk the small rows 

 unite and form two broader bands; but outside of these are also found more scattered rows of zooids, 

 so that there is hardly any quite naked dorsal and ventral surface of the stalk. From this fact it 

 follows, that only the zooid-less part of the bulb corresponds to the peduncle of other Penuatulids, and 

 that the greater part of the stalk from the beginning is to be regarded as the rhachis; to restrict this 

 name to the widened upper end bearing the polyp-cluster, as has been done hitherto by all authors, is 

 in reality misleading; I therefore designate this part as the rhachis-club. 



The polyp-cluster in the younger stages is always quite distinctly bilateral, often (oftenest?) also 

 asymmetric, and the terminal (primary) polyp is always evident as such; in the large colonies the 

 cluster is apparently radiate, and the terminal polyp is often not to be determined with certainty. A 

 closer inspection shows, however, that the polyp-cluster is still bilateral, and this fact may be discerned 

 whether the terminal polyp may be made out with certainty or not. 



In the younger colonies the upper end of the rhachis-club is seen to continue as a broad belt 

 of zooids directly to the base of the polyp, that is the primary individual. The upper end of the cal- 

 careous axis runs originally under this belt of zooids; from the structure of the primary individual 

 this belt must be determined as dorsal (Danielssen, like all other recent authors, follows Kolliker here 

 also, and uses the expression ventral); on the opposite -- accordingly ventral -- side of the rhachis- 

 club new polyps arise, often not in the ventral median line, but beside it. In my youngest specimen, 

 Nr. i, three developed polyps and a small rudiment (i-5 mm high) are placed below the terminal polyp 

 (fig. 46 P.), but otherwise of the same mutual height; of the developed polyps the terminal polyp is 

 the smallest. To the left of the terminal polyp are two developed polyps, to the right, one polyp and 

 the small rudiment; these (3^1) polyps represent evidently only the lower circle of polyps in a devel- 

 oped cluster; the tongue-shaped groups of zooids on the rhachis-club between the bases of the polyps 

 of the lower circle of the cluster are indicated in the following way: besides the dorsal belt of zooids, 

 which has not yet assumed the tongue-shape, there is only a distinct tongue-area between the two 

 polyps of the left side (fig. 46 t), and a quite slight indication on either side of the rudiment. 



The other young stage, Nr. 2 (fig. 47), has six polyps below the terminal polyp somewhat dif- 

 ferently developed, and in addition four small rudiments; all these six polyps and the rudiments still 

 only represent the lower circle of polyps of the large clusters; nor are the rudiments found here in 

 the ventral median line of the rhachis-club; the fact is that four developed polyps are found to the 

 left of the terminal polyp, to the right only two (figs. 47—49: 1, 2); the two polyps between which 

 the rudiments are found are evidently last developed, being both shorter and more slender than the 

 others, the terminal polyp included; this latter is likewise also smaller than those nearest to it. The 

 rudiments are of different sizes, so that they are seen to have arisen alternately to the right and 

 to the left. Corresponding to the arrangement of the polyps, the rhachis-club — besides the dorsal 

 belt (dt in figs. 47, 48, 49) — shows three distinct tongues of zooids (t, fig. 48) on the left side decreas- 

 ing in size towards the rudiments, one on the right side; in the rudiment-zone (fig. 49) there are slight 

 indications of as many tongues as there are buds. In the cluster, at the ventral base of the terminal 

 polyp are two zooids provided with a tentacle; one of them is very large (fig. 47, z), and its tentacle 

 has one lateral branch. 



