416 
Mr Menon, Notes on Semper s Larvae. 
With regard to the relation of the Zoantheae to other groups, 
Van Beneden, after a most careful study of Semper’s first larva, 
came to the conclusion that the Zoantheae are not related to the 
Actiniaria through Edwardsia , but that they form a group quite 
distinct from the others. McMurrich, Boveri, and others, on the 
other hand, consider that the Zoantheae are allied to the other 
groups and derive them with the others from a common Edwardsia 
stage. Goette in a recent contribution is inclined to unite them 
with the Ceriantheae and the Antipatharia, and to derive them 
from a common hexamerous type, while all the other Anthozoa 
are derived from a common octomerous type. 
It seems impossible to maintain that the Zoantheae are derived 
from an Edwardsia type. Whatever the relations of this group 
to the other groups associated with it by Goette may be there 
can be no doubt that it is widely separated from the Actiniaria 
which are derived from the Edwardsia type. As the six-mesen- 
tery stage is the characteristic stage in their development, the 
Zoantheae have to be derived from a hexamerous type. In as 
much as the six mesenteries of this stage are homologous with 
the first six mesenteries of the Edwardsia stage, the two types 
must be considered to have had a common line of descent. While 
the Zoantheae branched off from the main stem at an early stage 
(the six-mesentery stage), the other groups did not branch off till 
a later stage ( Edwardsia ) when there were eight macromesenteries. 
In connection with this early isolation of the group it is interest- 
ing to note that the larvae of the Zoantheae have retained what 
must be considered a primitive feature in their longitudinal and 
transverse ciliated bands. These bands are vestiges of a condition 
common to the ancestors of the Anthozoa and the Ctenophora, and 
characterised by the presence of longitudinal bands of long cilia 
in addition to a uniform covering of small cilia. In the Cteno- 
phora these bands became modified to form the eight rows of 
swimming-plates. In the larvae of the Zoantheae they were 
reduced to a single band, or to their oral ends which fused 
together to form a circular transverse band. 
REFERENCES. 
(1) E. Van Beneden. Une Larve voisine de la Larve de Semper. 
Archiv Biol. Tom. x. 1890. 
(2) McMurrich. On the development of the Hexactiniae. Abstract 
in Zoologischer Jahresbericht, 1891. 
(3) A. Goette. Einiges liber die Entwickelung der Scyphopolypen. 
Zeit. wiss. Zool. Bd. 63, 1898 (pp. 354 and 357). 
