12 
the voecium and the wall of the zooecium. It commences as two 
distinet processes from the lateral walls which finally coalesce. In 
Fl. (Membr.) flustroides, whose o0ecia project on the zooecial sur- 
face- this band subequently increases in height and at last covers 
the whole front part of the ocecium. In the family Farciminariidae 
the construction and the position of the ooecia are mainly the same 
as in Flustridae, but the ocecia always project on the surface of 
the zooecium. In the group of species represented by Farc. magna 
the superior part of the ocecium is on each side covered by a 
little vaulted calcified plate projecting from the lateral wall and 
seated between the ocecium and its covering membrane. 
To this type we provisionally refer a number of ocecia found 
in very different families and as far correspondent with the ooecia 
in the Frustridae that they are seated internally between two zooe- 
cia and are coalesced with an incompletely developed distal wall. 
For want of suitable material I cannot at present give any infor- 
mation about the membranous or muscular parts of these o00ecia. 
While the covering zooecia in a number of forms (f.1i. Micropora co- 
riacea, M. perforata, Lepralia sincera, Catenicella pulchella, C. pu- 
silla, C. gracilis, C. formosa etc.) are autozooecia, in most cases 
they are kenozooecia.  Qoecia covered by kenozooecia are found in 
most members of the family Diazeuwxidae, and besides within a 
number of different families, mamely in the Bicellariidae (Didymia 
simplex, Eucratea chelata, Bicellaria infundibulata), Cellulariidae 
(Menipea crystallind, M. cervicornis), Cribrilinidae (Cribrilina punc- 
tata, Cr. Gattyae), Mucronellidae (Mucronella diaphana, M. abyssi- 
cola) and Catenicellidae (Catenicella plagiostoma, v. setosa, C. ventri- 
cosa, C. margaritacea etc.). In all the here named forms the zooecial 
operculum when opened to a certain extent closes an opening whose 
proximal margin is the hingeé-line of the operceulum while distally 
it is limited by the free margin of the oocecium. It is the outer 
opening of a space which can be regarded as a fore-court common 
for the zooecium and the oocecium and which we will name an 
atrium, While Jullien has found no polypide in the oceciferous 
