320 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



left three rounded cells, one of which is vacuolated, the 

 other two contain chlorogogen granules. These may be 

 amoeboid cells which had temporarily withdrawn their 

 pseudopodia. x 1000. 



Fig. 45. A portion of the third diaphragm, from a 

 stained preparation, to show the numerous oval apertures 

 by which the septum is perforated. The diaphragm is 

 covered on both faces by a flattensd endothelium between 

 which is a thin layer of connective tissue and inter-crossing 

 muscle fibres. The endothelial nuclei of one face only are 

 shown. x 300. 



Plate VI. 



Fig. 46. Dissection of anterior end of large 

 specimen, with pharynx and the first diaphragm removed, 

 showing anterior and posterior lobes of brain ; middle 

 cerebral region of each side connected by broad band of 

 nervous tissue ; nerve to otocyst arising from oesophageal 

 connective ; muscle strands from otocyst to body wall ; 

 anterior portion of ventral nerve cord ; first notopodial 

 sacs and muscles ; the longitudinal muscles and the buccal 

 sheath, x 6. 



Fig. 47. Horizontal section of prostomium of a 

 specimen 60 mm. long. The anterior and dorsal portions 

 of anterior lobes of the brain are formed largely of pyri- 

 form ganglion cells shewn diagrammatically in the figure. 

 Three ccelomic spaces, lined by ccelomic epithelium and 

 containing blood-vessels, are seen. On the anterior left 

 side of brain is an eye slightly exaggerated. The posterior 

 lobes of the brain underlie the nuchal organ, most of their 

 nerve cells are small and their nuclei only are shown. 

 The middle region of the brain, consisting largely of 

 neuropile (finely punctate), shows a transverse band of 

 fibres connecting the right and left halves. Attached to 



