CERIANTHARIA. 



Strongly developed here, more so than in any other mesenter\-. The end of the craspedoneme region 

 forms here as with the metamesenteries of the 3rd and 4th cycles the most prominent portion, a 

 long lobe with numerous craspedonemes on the oral side and with wavy coils of the cnido-glandular 

 tract on the aboral side. 



Protoniesenteries 2 and 3 take with respect to their appearance a middle position between the 

 metamesenteries of the and and 3rd cycle. 



The metamesenteries are arranged in the usual manner: 4 mesenteries in each quartette (i, 3, 

 2,4—1,3,2,4 etc.). Broadly viewed the length of the mesenteries diminishes in every group in pro- 

 portion to its nearness to the multiplication chamber, which is shewn in the diagram of the arrange- 

 ment of a part of the right side metamesenteries. One peculiarity is worth pointing out, namely, 

 that between the 20th and 21st mesenter\- on the right side an extra mesentery has been developed 

 (text-fig. I. X.) which has the same appearance as the metamesenteries of the ist cycle, though it is 

 rather shorter, but is distinguished from them b)- the fact that it is sterile like tlie metamesenteries 

 of the 3rd and 4th cycles. This anomaly has nothing corresponding to it on the left side, as no such 

 mesentery exists there. This however is not the only break in tlie regular diminution in the size of 

 the mesenteries as they approach the multiplication chamber. Thus the mesentery of the 2nd c\cle 

 on the right side in the 6th group is longer than the corresponding mesentery in the 5th group. In 

 the i6th group on the same side the mesentery of the 2nd cycle is considerably longer than the 

 same mesentery of the preceding quartette and as long as the mesentery of the 2nd cycle in the ist 

 quartette — relations which remind us of those we meet with in Cerianthus membranaceiis and solitarius. 



The metamesenteries of the ist cycle (PL 2, i^'ig. 6) are those which principally develop re- 

 productive organs. They are very long and reach almost to the aboral portion of the bod}'. With 

 exception of the yoimgest of all they exhibit no difference in size and appearance. The repro- 

 ductive organs are best developed in the middle portion, where they take ui) the greater part of the 

 breadth of the mesenteries, rather feebler in the lowest part of the mesenteries and feeblest in the 

 straight part of the ciliated tract region, where onh- scattered germ follicles are found. The ciliated 

 tract region of the filament is straight for some distance under the stomatodaeum and then quickly 

 passes over into a folded section, which soon sends out craspedonemes. These are in the oral part 

 rather short (PI. 2, Fig. 7), in the lower parts however con.siderably longer and more branched, espe- 

 cially towards the proximal end, where they terminate in a cluster of threads [bni PI. 2, Fig. 8). At 

 the bottom of the mesentery is found an extremely minute part, a cnido-glandular tract of precisely 

 the same structure as the wavy part of the mesenteries of the 2nd and 4th cycle. In consequence of 

 its slight extent it is not marked in Fig. 8. The more or less concave aboral border of the mesen- 

 teries has no filament, as usual with mesenteries of every kind. 



The metamesenteries of the 2nd cycle (PI. 2, Fig. 4) closely recall those of the ist cycle though 

 they are much shorter, to a certain extent they form a transition to the mesenteries of the 3rd cycle. 

 The reproductive organs are only feebly developed on these mesenteries. As regards the length of 

 the different mesenteries of this cycle they follow the general rule with the exceptions before men- 

 tioned. It is possible indeed that in other groups besides those mentioned, an irregularity in the ratio 

 of the lengths of the mesenteries ma>- occur, as in this, the only fully serviceable specimen, I have 



The Danish Ingolf-Expediiion V. 5. 



