9 
MUSEUM OF COMPARATIVE ZOOLOGY. 33 
method of budding (Loxosoma); a relatively poorly developed, incom- 
pletely retractile lophophore; a complicated system of sense organs 
and nerves (Loxosoma); sexual and excretory ducts; a typical larval 
(trochophore) form, — these distinguish the Endoprocta. On the other 
hand, the Ectoprocta are marked by a loss of individuality (existence 
of coonoceel, Phylactolemata), by a highly complicated lophophore pro- 
vided with means for complete retraction, by absence of a complicated 
nervous system (small ganglion of Gymnolemata), by absence (2) of sex- 
ual and excretory ducts, and by abbreviated larval life (passed within 
the body of the mother). 
Stronger than this argument is the fact that in the development of 
the tentacular corona and of the alimentary tract — at first without a 
cacum — Ectoprocta pass through stages more nearly resembling the 
adult Endoprocta condition than their own adult condition does. 
These facts seem to me to prove, if morphological principles can be 
relied upon, that Endoprocta are nearer the ancestral form of Bryozoa 
than Ectoprocta. 
Admitting that the Endoprocta are more ancestral than the Ecto- 
procta, I cannot conceive how any one can maintain a close relationship 
with Phoronis. For the line connecting mouth and anus is in Endo- 
procta ventral, while the corresponding line in Phoronis is dorsal, as 
Caldwell (83, p. 372) has shown, and the kidney is a metanephridium. 
These facts far outweigh, in my opinion, similarities in tentacular corona, 
epistome, and bent alimentary tract. 
The absence of a true body cavity, and the existence of a water or 
excretory system ending in flame cells, point conclusively to an origin of 
Bryozoa from the lowest worms. For such an excretory system is found 
elsewhere only in Platyhelminthes, Rotifera, and in a modified form 
in Nemertines (Bürger, 91). On the other hand, the existence in the 
stalk of epithelial (in addition to mesenchymatous) muscles looks like 
an advance beyond Rotifera and Platyhelminthes. But it does not fol- 
low that such muscles existed in the ancestors of Endoprocta; they 
may have been produced by causes similar to those by virtue of which 
they occur in Nematodes. 
Hatschek (77, p. 528) suggested, and Harmer (85, p. 11, 35) has 
since shown, that the ganglion of the Endoprocta is to be regarded as a 
suboesophageal ganglion. Zelinka’s (91, p. 337) discovery of a subo- 
sophageal ganglion in Rotifers is interesting in this connection, as mak- 
ing more probable the assumption necessary for the preceding view, that 
the ancestor of Rotifers and Endoprocta possessed such an organ. 
