46 Journal of Entomology and Zoology 
the form of a U, with the concavity fitted to the anal side of the 
oesophagus in an oblique position with arms turned slightly up- 
wards. The end of each makes a turn in the oral direction, and is 
continuous with a large nerve trunk which goes to the lophophore 
arm. The ganglion is in direct connection with the inner cell layer 
of the oesophagus, the outer layer of the latter enveloping it on all 
sides. The lophophore nerve trunks are likewise located between 
the outer and inner layers of the body-wall; they run beneath the 
outer layer of the lophophore covered below by epithelium. The 
ganglion contains a large cavity extending to the ends of the gan- 
glion. The wall of the ventricle is very thin and epithelial in 
nature on all sides but the bottom on the anal side, where it is very 
thick as it joins the main part of the ganglion. This thick portion 
is distinctly separated from the epithelial part and is well seen in 
the fresh state as a somewhat reddish mass with a slight constric- 
tion in the median plane of the polype. It is this part that Hyatt 
took for the ganglion which he described as composed of two lateral 
masses connected by a thick commissure. The epithelial part is 
hard to recognize in surface views. A cross section of the lop- 
hophore trunks is kidney-shaped; in it the nerve cells are much 
crowded; the nerve cells are spindle-shaped, bipolar, with nuclei 
in the middle, closely packed together with few fibers between. 
The nerve trunks are thick and large as compared with the ganglia. 
The matter of a circum-oesophageal ring was not settled; this 
author did not find it. The colonial nervous system found in some 
marine Bryozoa for the purpose of controling the movements of 
the members of the colony seem to be entirely lacking in the species 
Pectinatella gelatinosa, and this fact agrees with the behavior of 
the animals as they act independently. 
Cori, 1893, does not give much further information about the 
nervous system of bryozoans. 
Delage and Herouard, 1897, in a number of diagrams show the 
position of the ganglion in marine ectoprocts as being a single small 
ganglion ventral to the oesophagus. There are probably nerves 
going to the tentacles, to the body and to the alimentary canal, but 
these are not clearly shown in any case. A ganglion in the avicu- 
larium is shown by Delage and Herouard and they indicate by a 
series of diagrams how this ganglion might have been derived from 
a single zooid by a series of gradual transformations. 
Ladewig, 1900, shows such a ganglion center in an avicularium 
of a marine ectoproct. 
The sensory system of ectoprocts has been described by 
Nitsche on the tentacles of Alcyonella as stiff bristles to which he 
ascribes the sense of taste. Verworn, Kraepelin, Braem and others 
have seen these without ascribing special functions to them. It 
seems probable that the tentacles must have some special sense 
organs for touch or other senses. 
