'3+ 



trace of any marked grooves at either end (Fig. I.). Its 

 surface is owing to thickenings of its walls ridged over those 

 mesenteries, which are attached to it. If 24 septa fuse in the 

 axial fossa, there should be 48 mesenteries of a first order 

 reaching the stomodoeum and corresponding to ridges. If a 

 less number fuse, there should be a proportionately lesser 

 number of mesenteries with ridges on the stomodoeum, but 

 this is not so, three polyps with 18, 20 and 21 such septa 

 having 48 mesenteries with ridges and one with 24 septa 50 

 such mesenteries. In a case with 20 septa (Fig. I.) two of the 

 mesenteries out of pairs on each side of tertiary septa have 

 failed to reach the stomodoeum, but their places have been 

 taken by others bounding quaternary septa. 



The lower edge of the stomodoeum is ill-defined and often 

 in the contracted pol3^p somewhat turned outwards {Fig. II.). 

 Its thickenings pass directly into the filaments of the corre- 

 sponding mesenteries, which form a first order. 



Fig II. Diagrdinmatical longitudinal section of a partially retracted specimen 

 of F. rubrum, th3 left half cutting a tentacle over a primary septum, expodng the 

 f dce of one of the bounding mesenteries, and the right half cutting a less retracted 

 tentacle over a quaternary septum and like iviie exposing the face of one of the 

 bounding mesenteries. 



The longitulinal lines on th3 faces of the mesenteries represent the distribution 

 and course cf the muscular fibres. Against the epithca their attachment in 

 clusters is, to some degree, shown. 



e. ?r. External body -wall. t. Ten'iacles. p. n- Wall of the peristoaie. st. 

 Stomodoeum. m. f. Mesenterial filaments, ff. Generative o-gans (ovary on the 

 I'ft and testis on the right mesentery), i?. Epitheca. <S 1 and S 4 septa of cycles 

 I. and IV., represented by incomplete lines. T. Trabeculae from the septal ed^e. 



Muscle?. — The muscles are of the usual Actinian type, but 

 the circular .sphincter is absent. The longitudinal muscular 



