REPORT ON ACTINIARIA. 247 



The mesenteries are arranged on the macrocnemic plan. In 

 two specimens I counted in each twenty mesenteries on one 

 side and twenty-one on the other. The shape of the perfect 

 mesenteries is somewhat peculiar. The basal portion of each 

 is thickened and distinctly club-shaped, the longitudinal mus- 

 culature being situated on one surface of this portion, and 

 from a little below the tip of the club a very thin lamella 

 begins, which terminates at its free edge in the mesenterial 

 filament and bears the reproductive organs when these are 

 developed (PI. in, Fig. 5). In one specimen examined, ova 

 were found in this thin portion of the perfect mesenteries and 

 there were no signs of spermatozoa, so that it mav be presumed 

 that the species is unisexual. The imperfect mesenteries 

 resemble the muscular portion of the perfect ones, the gono- 

 phoric lamella and the mesenterial filaments being wanting. 

 Xo basal lacunae occurred in any of the mesenteries. Owing 

 to the width of the stomatodaeum and the consequent small 

 space between it and the inner surface of the column wall 

 the mesenteries are narrow, a feature especiallv noticeable 

 in sections below the level of the stomatodaeum since the 

 mesenteries project only a relatively short distance into the 

 coelenteron and thus leave a large empty space in the center 

 of the column. 



The sphincter muscle (PI. 111. Fig. 4) is imbedded in the 

 mesoglcea and is strong, especially that portion which is con- 

 tained in the wall of the introverted portion of the column. 

 At its upper end it is composed of numerous elongated cavities, 

 whose long axes are at right angles to the column axis; further 

 down the cavities become smaller and oval, though still occupv- 

 ing a considerable portion of the thickness of the column wall. 

 but below the introvert it becomes rapidlv reduced to a single 

 row of small oval cavities which approach the endodermal 

 surface of the mesoglcea as they are traced downwards. 



The form which approaches this most nearly is that de- 

 scribed by Erdmann ("85) as species 4. and named bv Hert- 

 wig ('88) E. stellaris. It was obtained by the •• Challenger" 

 off one of the Philippine Islands. In the general form of the 



