236 
specimen of B. iverneri examined). I have also sectioned a spec- 
imen of annulata from Bermudas and one of Duerden’s spec- 
imens from Jamaica, and there was a mesogloeal sphincter in both 
(Duerden’s description of the arrangement of the mesenteries 
agrees perfectly with the observations I have made on the Baha- 
mas-specimens, so that there is no doubt that they belong to one 
and the same species), According to McMurrich (1889) and 
Pax (1910) Åiptasia (? Bartholomea, Stephenson 1920) tagetes 
has no sphincter, according to Watzl (1922) a mesogloeal one. A 
Control examinations of two Bahamas specimens examined by Watzl 
confirms the correctness of his observations. A specimen determ¬ 
ined by Duerden as Å. tagetes and received from him is also 
provided with a mesogloeal sphincter. For comparison I have also ex¬ 
amined Åiptasia diaphana, mutabilis and saxicola, of which the first 
(O. a. R. Hertwig 1879) and the second (Simon 1892) should 
be without a sphincter. Saxicola (1 spec. examined) as well as dia¬ 
phana (2 spec. examined) are however like the other species pro¬ 
vided with a mesogloeal sphincter. 
How are we to interpret these various statements? Is there in 
one and the same species a variation from no sphincter to a weak 
mesogloeal one, is there one species described under different spec- 
ies-names or do the various statements of the presence or absence 
of a sphincter depend upon erroneous observations? In the cases in 
which I have been able to control the observations, f. inst. of Duer¬ 
den’s specimens of lucida, tagetes and annulata, erroneous observ¬ 
ations explain the differences. Although I am mostly inclined to re- 
gard the many differences concerning the nature of the sphincter as 
depending upon less exact observations — it is, in faet, often dif- 
ficult to discover the sphincter in strongly expanded specimens, 
especially if the sections are somewhat obliquely cut, — the pos- 
sibility is not quite exeluded that a variation concerning the sphinc¬ 
ter can oceur and that some authors have described one and the 
same species under two different names. 
Also concerning the distribution of the reproductive organs the 
statements of different authors variate, no doubt owing to incom- 
plete observations, possibly also to the faet that the specimens were 
examined at the end (or beginning?) of a reproductive period. As 
to first Åiptasia couchii I have not been able to decide, if the main- 
