'45 



regeneration from the still attached stalk as in Fiingiay. 

 Cycloscris^ and probably many other genera. 



Polyps — (Text-Figures III. and IV.j. — The greater part of 

 the collection was forwarded to me in formalin. For the 

 determination of the species it was necessary to dry and 

 clean a considerable number of the adult specimens. To study 

 the development of the septa and corallum I had to do the 

 same to some of the smaller forms. The earliest of these 

 with 6 large and 6 small septa appeared, as if the tissues of 

 the polyp had been torn off the mouth of the calicle.t All. 

 the specimens of the young forms seemed to have suffered 

 greatly, and I rejected one after another as useless for section, 

 cutting, placing them in the cleaning bath. Finally I 

 selected a young polyp, which from surface view appeared to 

 have been torn around the base of the tentacles where they 

 run into the external body wall, there being no visible trace 

 of tentacles, peristome or stomodoeum. The central part of 

 the calicle was filled in with a mass of the irregularly coiled 

 mesenterial filaments, which I hoped might show the 

 structure. On cutting a series of transverse sections the 

 whole polyp turned out to be thoroughly well-preserved. So 

 far as I can see, there is no trace whatever in the polyp of 

 any rupture or tearing off of any part of the body wall, be- 

 yond what is clearly due to the perforation of the latter by 

 the upper, sharp edges of some of the septa. 



Fig. III. Transverse eecHons through the attached post-larval stage of F. 

 riihrum, described in <he text, in four different planes, shown ay^ proximately in 

 Fig. IV. (drawn under the cam- ra lucida). 



A. shows the connection of the cavities of the different systems at the base of 

 the polyp. Only trace*" of me-entpries are present by three of the septa. B. repre- 

 sents half the sa'r-e at a higher level. The primary septa alone fuse in the axial 

 fossa. The first 12 mesent-^rie* are complete and the second 12 have corampnced. 

 C. and D. represent the same quadrant, C. where the primaiy and t^econdarj- septa 

 both fuse by trabeculae and D a little higher. 



The numerals refer to the cycles of the septa. T. Trabeculae from the 

 septal edges. * 



* Vide WilUtfs Zoolngical ReeuHs, pp. 171-180 and plates XIX and XX 

 t Two other specimens, since found, corroborate the development as described 

 in the following pages. They are both of a considerably earlier stage. 



