460 THE NERVOUS SYSTEM. 



' The superior capsule descends, behind, to the same level as 

 the inferior, except in the middle line, where it is deeply 

 notched ; on either side of this notch a short peduncle arises, 

 which immediately expands into a spherical tubercle, the 

 tubercle of the corpus centrale. The opposite tubercles are 

 united with each other by a short fibrous fasciculus.' In the 

 Blow-fly the peduncles of the corpus centrale are apparently 

 longer. I have not been able to recognise any tubercles upon 

 them, but they evidently have connections with the thalamic 

 lobes as well as with the crura (see PL XXXI., Fig. 2). 



The Cortex of the Brain. The cellular cortex of the brain not 

 only covers the whole surface with a layer of variable thickness, 

 but it penetrates the interior and becomes continuous with the 

 great pyramidal ganglion, with the lamina of gray matter 

 surrounding the corpus centrale, and with that surrounding 

 the thalamic and procerebral lobes. 



The cortex consists of cells similar to those of the thoracic 

 ganglia, but the optic ganglia and the posterior part of the 

 cortex are formed almost entirely of small round cells similar to 

 the cortical cells of the cerebellum, and to those of the nuclear 

 layers of the retina in the Vertebrata. 



The whole superior and posterior region, in which tin >< 

 small cells are largely developed, is divided into four very 

 remarkable areas, two on each side, known as the corpora 

 fungiformia. 



The rest of the cortex is not divided into distinct areas, but 

 groups of large stellate cells occur around the roots of the 



or PLATI-: XXXII. 



Fn;. i. A frontal section of the brain of the Hlow-fly, with a slight obliquity from 

 above downwards and behind forwards, behind the nudulus. The upper half of 

 this section is behind, and the lower half in front of the plane of the section seen 

 in I'late XXX., Fig. I. a, antennal ganglion; c /, c /, f I, lobes of the pro- 

 cerebron ; ///, thalamic lobe ; in, in, HI, superior lobe of the mesocerebron. 



Kir,. 2. A similar section through the corpus centrale from the same brain : c c, 

 o.rpus centrale; cr, f, brachium of the corpus centrale; i, infia-n.-sophagt.-al 

 (crural) ganglia ; tr, trabccula. The other references as in Fig. I. 



FlG. 3. A lateral section of a I How-fly's brain through the lower part of the corpus 

 centrale : ///, mesocerebron ; ;//, metacerebron ; o s, optic, peduncle. The other 

 letters as in Figs, i and 2. 



