i6o Records of the Indian Museum. [Vol.. Ill, 



transverse muscle-fibres. I ha\'e not been able to detect longitudinal 

 muscles in the mesenteries at any point. The swollen appearance 

 of the central part is due solely to enlargement and vacuolation 

 of the endoderm cells which form the bulk of the mesentery. These 

 cells have very minute nuclei, which are situated at their free 

 edge. 



The outlines of the mesenteries in transverse section are im- 

 portant in relation to the position of the mesenterial mesoglcea. 

 In few mesenteries does this occup}- the middle line exactly, but 

 in nearly all cases it is slightly nearer one surface than the other 

 (plate ix, figs. 5, 6). ^loreover, the surface from which it is most 

 remote can in most cases be seen to be more broadh' convex than 

 that to which it is nearest. All the mesenteries, therefore, may 

 be said to point in one direction. This direction is that most re- 

 mote from the apex of the ciliated groove. 



The mesenteries decrease in transverse length at either end 

 of the stomodaeum, those at the apex of the ciliated groove being 

 not quite so short as those opposite them. 



The mesenterial filaments are less strongly contorted than 

 is the case in many Actinians. On some mesenteries they run 

 almost straight from the lower end of the stomodseum to the base 

 of the mesentery, while in others they are contorted only in the' 

 middle part of their length. The longitudinal groove running down 

 the upper part of each filament is deep, and the corresponding 

 ridge on the middle part high ; otherwise the minute structure 

 of the filament offers no particular feature of interest. 



Some of the mesenterial filaments are continued at the lower 

 extremity of the mesentery so as to form acontia, which can be 

 thrust out of the basal pore or even of the mouth ; but the acontia 

 are much shorter than is usually the case in the Sagartiidse, and, 

 moreover, do not seem to be particularly w^ell supplied with nema- 

 tocysts, although those structures occur in them in considerable 

 numbers. So far as I can find, neither the number of the acontia 

 nor the exact mesenter}'' to which each is attached is in an)^ wa}' 

 a constant character. There are no acontia-like filaments on the 

 upper part of the mesenteries. 



There are no mesenterial foramina. 



Gonads ^ are absent from all the specimens I have examined, 

 but, as I have already pointed out, this may be due to the fact 

 that my specimens were not collected during the breeding season. 



Biology 



Anactinia does not appear to have any means of independent 

 progression, and my specimens exhibited no movements except 



1 In a specimen taken by Dr. J, Travis Jenkins on the surface of the sea about 

 10 miles off the Orissa coast oti February 20th, 1909, immature testes are present. 

 They occur on some qf the mesenteries, not on all ; there appears to be a tendency 

 for fertile and infertile mesenteries to alternate, but this rule is not without ex- 

 ceptions. — March 3rd, 1900. 



