I40 McMURRICH. [Vol. IV. 



appeared, and in a section slightly below the middle of the 

 column only the mesenteries of the first grade would be found. 



In a section a little higher up than the third (Fig. 5) of those 

 figured, on the gonophoric mesenteries, just before the mesen- 

 terial filaments die out, a very small portion of the " Nesseldrii- 

 senstreif" can be seen. It is histologically like the same 

 portion in the mesenteries of the fourth grade, but does not 

 reach anything like the development it has upon these latter 

 mesenteries, being of very small extent, and somewhat apt to 

 be overlooked. 



It will be seen from what has been said that the mesenteries of 

 the fourth grade are noticeably different from those of the other 

 three grades with which they alternate. They are much 

 shorter ; they never bear reproductive elements ; and they 

 possess both the " Flimmerstreifen " and the " Nesseldrusen- 

 streif " of the mesenterial filaments well developed. On the 

 other hand, the mesenteries of the first three grades are all 

 gonophoric, and their filaments consist almost entirely of the 

 " Flimmerstreifen," the " Nesseldriisenstreif " being very 

 short. 



C. membranaceus has been found to be hermaphrodite by all 

 who make statements on this point, the ova and spermato- 

 zoa being both present upon all the gonophoric mesenteries. 

 C. borealis, Danl. is, according to its describer, bisexual, and 

 C. Americamis agrees with it. Agassiz, as already noted, states 

 that this last form is hermaphrodite, the ova occurring in the 

 upper part of the mesenteries, and the spermatozoa lower 

 down ; but this is certainly not the case in the three specimens 

 I had for study. All were females, ova only occurring in the 

 gonophoric mesenteries, and sections taken at varying distances 

 down the column to within 2 mm. of the posterior extremity 

 show no trace of spermatozoa. 



Of course it is possible that C. Americamis may be dichog- 

 amous, as Lacaze-Duthiers ('72) believes the Hexactinias to be. 

 In all the Actinians which I have examined, amounting to over 

 fifty species, with the exception of certain Zoantheae, which are 

 known to be hermaphrodite, I have never found any trace of 

 dichogamy or hermaphroditism. If dichogamy occurred as a 

 rule, one would expect to find occasionally, at any rate, some 

 traces of spermatozoa associated with ova, or of ova with sper- 



