PHYLUM MOLLUSCA 



747 



bands of nerve-matter pass round the oesophagus to unite with the 

 pedal and pleuro-visceral ganglia, which lie behind. The pedal 



ganglia (Fig. 676) are, like 

 the cerebral, united into a 

 single mass ; orally this is 

 prolonged and expanded into 

 a broad mass from which the 

 ten brachial nerves (br. n.) are 

 given off to the arms. The 



p f ~ 



brccx.r 



Lclen. 

 la. 



Lb 



Fia. 672. Sepia cultrata, lateral dissection of male. 

 The left-hand half of the head has been removed by an 

 approximately median longitudinal section, the buccal 

 mass, however, being left intact ; the funnel and the 

 anterior and posterior walls of the mantle-cavity are 

 likewise bisected longitudinally. The left ctenidium with 

 the left renal sac and left branchial heart have been 

 removed from their natural position and displaced back- 

 wards so as to expose the other organs. The digestive 

 gland with its ducts and the pancreatic appendages have 

 been removed, but the position of the former is indicated 

 by a dotted line . app. appendage of left branchial heart ; 

 aort. aorta ; aort'. aboral aorta ; buc. buccal mass ; br. cart. 

 section of cartilage supporting the arms ; cer. g. cerebral 

 ganglia ; giz. caecum ; ink. s. ink-sac ; inf. funnel ; jaw, 

 jaw ; 1. aur. left auricle'; I. br. ht. left branchial heart ; 

 /. cten. left ctenidium ; liv. position of digestive gland ; 

 1. neph. left renal sac ; n. cart, nuchal cartilage ; oes. 

 oesophagus ; ot. cavity of statocyst laid open ; ped. g. 

 section of pedal ganglion ; perist. points to circular lip 

 with peristomial membrane surrounding it ; post. v. abdo- 

 minal vein ; r. aur. right auricle ; r. cten. right ctenidium ; 

 reel, rectum ; sal. salivary gland ; sh. shell ; st. stomach ; 

 te. testis ; va. valve of funnel ; v. cav. vena cava ; vent. 

 ventricle. 



pleuro-visceral ganglia, also united into one, 

 contact with the pedal behind the oesophagus. 



FIG. 673 Sepia officinalis, 



longitudinal section of ink- 

 sac, a. anus ; d. ink-duct ; 

 i. g. ink-gland ; i. r. cavity 

 of ink-sac ; o. orifice of ink- 

 gland ; r. rectum ; sp. sphinc- 

 ter muscles. (From the Cam- 

 bridge Natural History, after 

 Girod.) 



are in immediate 



