56 PHYSIOLOGICAL SERIES. 



the lateral body-walls, while the ventral and posterior parts 

 of the bocly ttervea mm the pedal ganglia. The 



buccal ganglia an- contiguou- in tin- mid-lino; they Ho on 

 tli.- posterior Mirface of the huce;d mass between the 

 hagus and radula--ac. and give off nerves as usual 

 to the huccal mass and alimentarv canal. 



D. 56. A Sea-Hare (.!/>///*/ sp.) opened longitudinally to the 

 right of the dorsal mid-line, and with the body-walls spread 

 to either side to show the nervous system In situ. The 

 viscera have been removed with the exception of the buccal 

 ma-- and part of the heart. The outlines of the ganglia 

 le-- distinct than in the previou- -pecimen, as the 

 coimective-tis-ue >heath by which they are enveloped has 

 not been removed. I're.-crved in Goadby solution. 



D. 57. Two specimen- of the nervous system of a Nudibranch 



iliita). The central system is extremely 



concentrated. It consists of a single supra-oesophageal 



tabulated ma , in which can be traced three pairs of centre- 

 that apparent!; :it cerebral, plciiral,and pedal ganglia. 



The (r.-bnd, which form the anterior part of the mass as 

 seen in the lower specimen, ^ive o<V. as usual, buccal connec- 

 ti\e- and ner\e- to the cephalic -en-e-organ<. The [ileural 

 and pedal centre- >upply the body-wall and generative 

 08. The lateral part- ol' the compound gan-lion are 

 united below the d->ophagn- by a triple commissure; two 

 .!' it- eon-titm-nt- ari-e in the pedal ganglia and correspond 

 to the t\\n p.-.lal c(.mmi--iire-oi'Tectibranch- (e.g. Aj>/> 

 the third (marked by black paper in the upper -pecimen) 

 unite- the pleural <-entr<- and may be regarded a- an 

 orthoiieuroii- \JM-rral loop. Q. ( . \'.\(^> \',n. 



D. 58. A Ntidihraiieh > lin),,l,,-,-,iii) \\ith the nervous 



d from abo\e. The central system con-i-t- 



L'lionie ma e- eom-entrated in a tran.-\ er>e 



the anterior end of the <c-ophagu-. Tin- 



inner pair are contiguous with one another in the dor-al 



mid-line; each n-piv-ent- a fu-icm of a cerebral with 



a pleuro-\i-crral centre. |.' rum ,| M . .,, ,.,.;,. (, .,,,.,,}..,!) 



