ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
317 
consists of radial sheets of fibrils, several of which dcvelope in a single 
cell. Many of the vacuolated cells of the stalk end in flame-cells like 
the excretory tubules of Platyhelminthes. Yolk is developed in the 
cells at the base of the stalk in the form of five intercellular granules 
which later fuse ; this process is accompanied by cell-degeneration. 
The lip of the atrium contains a sphincter, and resembles in its rela- 
tions the so-called margin-thickening of the Ectoprocta. The epithe- 
lium of the tentacles encloses a parenchymatous core ; a pair of muscles 
is present. The alimentary tract resembles generally that of the 
Pedicellinidse. The nephridial tubules, which end blindly in flame- 
cells, open, with the anus and vas deferens, into a cloaca. 
From the Urnatella-stalk there arise two kinds of buds ; 
“ branches ” which are typically median, and “ stolons” which are 
typically lateral. The segmentation of the stalk is probably an adapta- 
tion to the process of budding, which is accompanied by a greater liabi- 
lity of the wall of the stalk to rupture, and, therefore, by a greater need 
for the separation of the stalk into compartments. 
In all Endoprocta the oral aspect of the buds is turned towards the 
centre of proliferation, and in all Bryozoa the aspect in which that end 
of the alimentary tract, which arises from the principal outpocketing of 
the atrium, lies is turned towards the gemmiparous zone. The stolons 
of the parent stalk of TJrnateUa habitually become free for the purpose 
of founding new stocks. 
The author regards this genus as one of the Pedicellinidse, and 
most nearly resembling Artliropodaria Benedeni. 
Embryology and anatomy both indicate that the Bryozoa are closely 
allied to Ihe Rotifera, the two groups having sprung from an ancestor 
common to them and the Mollusca. After the Rotifer-stem had branched 
off, the Mollusco-Bryozoan stem produced tentacles on the lateral 
ridges ; the two groups soon separated, and the Bryozoa remained at a 
low level. The chief changes which the group has experienced are the 
acquirement of a body-cavity, the loss (?) of the protonephridia and sexual 
ducts in the Ectoprocta ; the loss of the epistome in the Gymnolsema ; 
the loss of the preoral ganglia ; and the multiplication of the methods of 
reproduction, by regeneration, budding, division of stocks and statoblasts. 
Nephridia of Cristatella.* — Dr. C. J. Cori has studied these organs, 
which were first seen by Verworn, by feeding and injecting Cristatellse 
with powdered carmine. They lie to the anal side of the oesophagus, 
imbedded in that part of the body- wall which clothes the lophophore con- 
cavity. They consist of two canals communicating by open ciliated funnels 
with the cavity of the metasome, and uniting in an expanded bladder- 
like efferent duct, which opens to the exterior. The structure of these 
nephridia is described in detail, and their resemblance to the similar 
organs in Phoronis is noticed. They are not in themselves excretory in 
the strict sense, but serve for getting rid of the waste-products borne by 
the lymph or separated peritoneal cells. 
y. Brachiopoda. 
Development of Brachial Apparatus of some Brachiopods.f— MM. 
P. Fischer and D. P. Oehlert, who have been able to observe the suc- 
* Zeitschr. f. wiss. Zool., lv. (1893) pp. 626-44 (2 pis.), 
t Comptes Rendus, cxv. (1892) pp. 749-51. 
