I0 CERIANTHARIA. 



not been able to study the mesenteries as closely as could be desired. The length of the mesenteries 

 below the stomatodaeum is about 2 / 7 V 5 of the distance between the aboral pole and the lower border 

 of the stomatodaeum. The straight part of the ciliated tract portion of the filament is shorter than 

 in the mesenteries of the ist cycle, but rather longer than the craspedoneme region. The craspe- 

 donemes are but slightly branched, in the most aboral portion packed close together in a bunch as 

 with the mesenteries of the ist cycle. At the bottom is a small part, a cnido-glandular tract which 

 in a number of mesenteries shews many coils, so that these mesenteries by their appearance suggest 

 those of the 3rd and 4th cycle. The mesenteries are broadest in the aboral part. 



The metamesenteries of the 3rd and 4th cycle (PI. 2, Fig. 3, 5) agree in structure with the 

 protomesenteries 3. They are distinguished, the one from the other, only by a slight difference of 

 length and position. The difference in size between the mesenteries of the same cycle is inconsider- 

 able in the various groups, but they follow roughly the usual rule, that they get smaller towards the 

 multiplication chamber. The straight part of the ciliated tract region is quite short, then follows a 

 slightly folded short region with craspedonemes which are continued on to a considerably projecting 

 portion of the mesentery, where they correspond to the bunches of craspedonemes which are present 

 on the mesenteries of the ist and and cycle. The bunch is less developed on the mesenteries of the 

 4th cycle than on those of the 3rd, and lies on the oral side of the projecting part of the mesentery, 

 whilst the aboral side of it is taken up by the greatly coiled part of the cnido-glandular tract. At 

 the extremity of the projection, the ciliated region and the cnido-glaudular tract pass into one another. 

 The mesenteries of the 3rd and 4th cycle are considerably broader than those of the ist and and 

 cycle. The broadest part is where the ciliated region terminates in the cnido-glandular tract. 



The mesenteries of the ist cycle then are fertile and have a long craspedoneme region and a 

 very short cnido-glandular region. 



The mesenteries of the 2nd cycle are likewise fertile and have a shorter craspedoneme region 

 and a short cnido-glaudular region, sometimes with many coils. The mesenteries of the 3rd and 4th 

 cycle are sterile and have a short craspedoneme region but on the other hand a strongly developed 

 wavy cnido-glandular region. 



The cnido-glandular tract is thus very feeble on the mesenteries of the ist cycle, rather 

 stronger on those of the the and, and well developed on the mesenteries of the 3rd and 4th cycle, 

 whilst the reverse is the case with regard to the ciliated tract region and its craspedonemes. 



The filaments in the region of the ciliated tracts recall, in point of structure, those in Ceri- 

 anthus lloydii described below. The thin-walled nematocysts are very numerous in the lateral por- 

 tions of the median streak, and very narrow but long nematocysts occur there also with very winding 

 thread. There is not found here so pronounced a ciliated groove between the two lateral portions of 

 the median streak as is found in A. oligopodus, but the middle parts consist principally of supporting 

 cells combined with scattered gland cells and spirocysts. In the craspedoneme region the median 

 streak shews no tendency to bipartition. Since the filament encases the free edge of the craspedonemes, 

 it is of course cut through twice by a transverse section (PI. i, Fig. 5). The craspedonemes are thus 

 constructed as in C. membranacnis. Nematocysts with coiled thread also occur here. 



