36 PHYSIOLOGICAL SERIES. 



brain, and apparently form? a nucleus to which fibres from 

 all parts converge. The most important tracts in con- 

 nection with it are derived from the fimgiform bodies and 

 optic arid antennary lobes ; beneath it lie a pair of small 

 neuropile masses the tubercles of the corpus centrale. 

 (The corpus centrale and tubercles are shown in the 

 drawing directly above the trabecula.) A similar though 

 simpler median band lies between the protocerebral lobes 

 in the Decapod Crustacea. 



The antennary lobes (deutocerebrum) consist of two 

 lobules on either side united by transverse commissure- : 

 the ventral of the two gives off the larger part of the 

 antennary nerve (probably olfactory) ; its neuropile is 

 glomerulated. A second smaller root of the antennary 

 nerve is derived from the dorsal lobule, it is chiefly motor 

 in function. A small tegumentary nerve rises from the , 

 anterior face of the ventral lobule. 



Each half of the tritocerebrum gives off a nerve from its 

 anterior surface that meets its fellow in the mid-line to 

 form a triangular ganglion (frontal ganglion, E) from 

 which a median nerve runs back along the alimentary 

 canal. 



These models, which were cast from originals recon- 

 structed from a series of transverse sections by Mr. E. T. 

 Newton, have been diagrammatically painted and have 

 certain parts and areas indicated by letters and numbers, 

 the key to which is mounted below the models. 



Newton, Quart. Journ. Micr. Sci., vol. xix. 1879, p. 340. 



D. 28. Two specimen- of a Cockroach (/il<i(fu aim'i-icami) dis- 

 -eted to show the nervous -y>tein from the dorsal and 

 ventral a-pect-. The dorsil -uri'ace is shown in the left-hand 

 -peeimen. tile ventral ill tile ri^llt. Tile cerehral ^an^lion 

 lies in the head, and i- -o placed that the optic lohes lie 

 vertically above the ant-nnary. The SuboMOphageal 

 ganglion for the in nervation of the mouth-part- is al>o 

 -ituated in the head do>e IK -low the cerebral; it is united liv 

 a pair of connectives to a ventral chain composed of 

 9 paired ganglia. The anterior three an- larger than the 

 re>t, and lie one in each thoracic segment at equal distances 



