114 SIDNEY F. HARMER. 
into the central body-cavity, and the embryo finally escapes as 
a larva provided with a larger or smaller number of polypides. 
In Lichenopora, on the contrary, the morula enlarges while 
retaining an embryonic, undifferentiated character in its cells. 
It then undergoes repeated fission, and the definitive secondary 
embryos produced in this way then acquire a two-layered 
character which is strikingly suggestive of the Phylactolema- 
tous embryo. 
In spite of the extraordinary resemblance between the “sus- 
pensor stage” of Lichenopora and that of Plumatella, I 
have not been able to convince myself that the result is arrived 
at, in the former, in the way described by Kraepelin for the 
latter. The structure of the embryophore in Lichenopora 
would indeed be most easily explained by supposing the 
‘* suspensor ” to represent the ectodermic part of a bud, but I 
have not been able to obtain any evidence that this is the case. 
There are, however, instances among marine Polyzoa where a 
new polypide-bud is formed in the immediate neighbourhood of 
the brown body (cf. 7, p. 140), instead of in close connection 
with the body-wall. It is possible that the Lichenopora 
suspensor may belong to this little-understood class of polypide 
buds, but I must emphasise the fact that I have no internal 
evidence tending to prove that it is a bud. 
Were it not for the very marked similarity of the early stages 
of the two groups there would be little reason for anticipating 
an agreement in detail between Cyclostomata and Phylacto- 
lemata, particularly as the details of Lichenopora are so 
different from those of Crisia, another Cyclostome. 
Kraepelin (10) has, moreover, urged a series of reasons for 
believing that the Ctenostomata, among the marine Polyzoa, 
are the nearest allies of the Phylactolemata. As I have made 
no special study of the latter group, I have arrived at no con- 
clusions of my own with regard to their affinities, but the 
details of their early developmental phenomena appear to me 
to be sufficiently similar to those of Cyclostomes to make it 
worth while to call special attention to the fact. 
One other suggestion may be made with regard to the 
