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 lojihophore 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 Ijy 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 i)lane of the iiolype. It is this jiart that Ilyatt 

 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 purpo.se of controling the movements of 

 the members of the colony seem to be entirely lacking in the species 

 PectinateUa (nUtdnosa, and this fact agrees with the behavior of 

 the animals as they act independently. 



Cori, 1898, does not give much further information about the 

 nervous system of bryozoans. 



Delage and Herouard, 1897. in a numl>er of diagrams show the 

 liosition of the ganglion in marine ectoprocts as being a single small 

 ganglion ventral to the oesophagus. There are probal)!y 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 aviculariuni 

 of a marine ectoproct. 



The sensory system of ectoprocts has been described by 

 Nitsche on the tentacles of AlcifoncUa as stiff bristles to which he 

 ascribes the sense of taste. Verworu, 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. 



