XXX Journal of Comparative Neurology. 



carnivora. Zachcr finds in addition degeneration in the brachium and 

 substance of the quadrigemina posterior. 



The Nervous Structlres of Tunicates. 



In a brief notice in the Johns Hopkins circulars XI, 97, April, 1S92, 

 M. M. Metcalf discusses the innervation of the ciliated funnel or dorsal 

 tubercle and the development of the sub-neural gland in Salpa. The 

 Salpas differ from the Ascidians in having the cavity of the central nervous 

 system, which is present only in the early development, continuous with 

 the lumen of the ciliated funnel. Running through the tissue of the brain, 

 especially the dorsal two-thirds, are many ramifying canals. The ramifi- 

 cations of the canals often anastamose and form a free communication 

 between the ciliated funnel and the space about the brain. They persist 

 but a short time, the brain soon becoming solid. The author believes that 

 the early function of the funnel \^'as the aeriation of the brain, \\ hile it 

 also perhaps served to carry off the waste products of the metabolism of 

 the brain cells. The later condition, especially its innervation, indicate 

 that the ciliated funnel is probably a sense organ, having, very likely, to 

 test the quality of the water entering the pharynx. 



At the time when the walls of the cloacal chamber begin to separate 

 from the brain two cell masses at the point of adhesion are drawn out 

 into tubes which become coiled and develop disc-like expansions near the 

 brain. About these discs there develop two clusters of cells of which 

 the anterior is composed of large cells resembling the cells of origin of the 

 nerves while those of the other resen.ble the peripheral nerve cells of the 

 brain. 



The Nervous System of Gasteropods. 



Erlanger describes the development of the nervous system in Paludina 

 as follows -A 



All the ganglia originate separately by delamination of the ectoderm. 

 Their connection is secondarily acquired by the outgrowth of commissural 

 fibres. The cerebral ganglion originates within the area of the velum 

 beneath the rudiment of the tentacles ; the pedal ganglia, on either side 

 the foot ; the pallial ganglion, somewhat ventrad and caudad to the 

 cerebral ; and the buccal from the ectoderm of the ctsophagus. The intes- 



1. R. V. Erlanger, Ziir Entwicklung von I'aliuliua vivipara. (Vorlaeutige Mit- 

 theiluug). ZooL Anzeiger, XIV, 357, Feb. 1891 



