8 4 



PENNATULIDA. 



broader; it is the dorsal belt of zooids, or, more correctly, the lower part of this belt; in several large 

 specimens it may easily and unmistakably, though as a narrow stripe, be traced between the npper 

 polyps to the base of a certain one, the original terminal polyp; in other specimens this tongue may 

 be traced to the end of the rhachis among the polyps, but which of these is the terminal polyp can- 

 not be determined with absolute certainty; not so much because this polyp has been atrophied, but 

 that it simply has been somewhat displaced during growth. The other zooid-areas are, as mentioned, 

 all somewhat smaller (narrower) than the dorsal one, but most conspicuously smaller are one, two, 

 or three areas on the opposite — ventral — side of the rhachis. In my specimen Nr. 5 the fifth zooid- 

 area to the left of the dorsal one is the smallest; in Nr. 6 the fourth and fifth are smallest, in Nr. 3 

 the fourth, fifth, and sixth; in Nr. 4 the sixth and seventh areas are quite narrow, and between their 

 upper end is a quite young rudiment (in form like a zooid, see below); in Nr. 8 the fifth and sixth 

 areas are also quite narrow, and between them is seen a quite young polyp; in Nr. 10 the sixth area 

 is divided above into two narrow points by a naked streak; at the upper end of this streak is found 

 an isolated large zooid (or a rudiment of a polyp). 



These smallest zooid-areas must show the region where the latest appearing polyps of the 

 lower circle are found, without regard to whether these polyps may have reached the same size as 

 those placed nearest to the dorsal tongue or not. The place corresponds also to the zone in the 

 younger stages where new individuals of the lower circle arise; and in the specimens Nr. 4 and 8 

 new individuals are seen to arise here, as well as new, quite narrow zooid-areas; but in Nr. 4 the 

 circumstance is to be noted that the new individual is formed like a zooid, whilst rudiments of polyps 

 of the same size elsewhere — the zooid in question is ca. 7 mm high on the side turned outward, ca. 

 2 mm on t ] ie opposite side — already prove themselves to be polyps by being provided with eight arms. 

 The question then arises here; do not in Umb. encrinus, some of the later polyps begin as zooids, or 

 - what is essentially the same thing — cannot some zooids by degrees be turned into polyps? It has 

 been indicated above that, among the numerous tentacle-bearing zooids which look like those of the 

 tongue-areas, are found a larger or smaller number of much larger zooids, several more than i mra high, a 

 few still much larger up to 5 mm , on that part of the rhachis-club which is more or less hidden by the 

 polyps (they begin to appear already in young clusters, see above Nr. 2); at the first glance, one cannot 

 help regarding them as young rudiments of polyps; but at the same time, individuals of a similar size 

 or not much larger may be found, which are decidedly rudiments of polyps, as they have eight 

 distinct arms, and corresponding to this another form of the mouth-lips. I have only in one case seen 

 a zooid which seemed to me to be in the act of turning into a polyp; in the large specimen Nr. 3, 

 directly at the upper end of the rhachis-club, is an individual, 4 ,nm high, provided with the two 

 mouth-lips of the zooids (but unusually large and conspicuous), and carrying four tentacles, two very 

 long and with pinnulse, two quite short and without lateral branches; the ventral tentacle is the 

 longest and most developed; next to it comes the right ventro-lateral one, whilst the left ventro- 

 lateral and the left lateral are quite small. This case, together with the one mentioned above in Nr. 4, 

 where a gigantic zooid is found in the very place of a polyp, might tempt one to answer the question 

 put above in the affirmative; it ought not to be forgotten, however, that these two cases may be 



