the Nervous System of Dipliyes. 



llo 



cesses, witli curtain-like flaps between them, bound the polype- 

 cell, including the apex of the distal nectocaljx. This latter 

 is also four-sided and laterally compressed, bearing the ])ro- 

 pulsive chamber or nectosae above, and a deep longitudinal 

 groove for the cliaplet of polypes beneath, while the free ex- 

 tremity terminates in a double-pointed projection. All the 

 angles and edges of both nectocalyces are faintly serrated, 

 with the points directed towards the base in each, so as to 

 offer little or no resistance to the water during natation. The 

 figure will give a suificient idea of the general characters of 

 this species, without further description, except what is to be 

 said of the nervous system, the exposition of which is the 

 principal object of this paper. 



At the base of the polype-cell, just within the attachment 

 of the coenosarc, and above the duct of the somatocyst, there 

 appeared to me to be a little ganglionic mass ; but of this I 

 cannot be quite certain until I investigate the matter a little 

 more closely. I am satisfied, however, that I have been able 

 to trace a nerve-trunk from that point along the inferior wall 

 of the polype-cell to the angle between it and the open end of 

 the nectosae, the upper wall of which is supplied with two 

 long and tapering nerves, bifurcating from the primary trunk. 

 A second principal nerve was distinctly traceable into the 



A, 



A, the proximal nectocalyx : a, polype-cell, lodging tlie coenosarc and 



polypes ; b, somatocyst, communicating with the coenosarc cavity ; 

 c, nectosae or propulsive chamber, 



B, the distal nectocalyx : a, protective groove for the polypes ; b, pedicel 



of the nectosae including the nerve ; c, the nectosae. 



C, chaplet of coenosarc and polypes. 



D, the nervous system : 1, nervous centre ? ; 2, proximal nerve-trunk ; 



3, distal nerve-trunk ; 4, branches to proximal nectosae ; 6, branches 

 to distal nectosae. 



