XII 



1. hepatic valve. 



2. intestinal valve. 



3. gastric valve. 



4. edges of the partition which separates the upper and lower lobes of the caecum, the 

 lower lobe having been removed with the adjacent portions of the lower wall of the stomach 

 and intestine. 



Fig. 3 Drawing (somewhat diagi'ammatic) of a median section of a sucker, from one of the central rows 

 of the tentacle. X 15. 



Fig. 4. Section of an unsynimotrical sucker. 



A. artery. 



M. marginal membrane of arm. 



iV. nerve. 



Pd. pedicle of sucker. 



JJi chitin ring. 



S. superficial brachial vein. 



V. vein of sucker. 



1. upper muscle of ring. 



2. lower muscle of ring. 

 3 sphincter muscle. 



4. columnar epithelium forming pit glands. 



5. columnar epithelium of the base of sucker. 



6. basal muscle. 



7. circular basal muscle. 



8. longitudinal muscle fibres of arm. 



9. transverse muscle fibres of arm. 



7. constriction at base of filament. 



8. contractile fibres of case. 



9. "spring". 



10. enlargement distal to constriction. 



11. filament. 



12. cavity around filament. 



13. cavities of case. 



Fig. 6. Arterial system , posterior aspect. 



Fig. 7. Left side of the digestive system. 

 AN. anus. 



BG. suprabuccal ganglion. 

 EGA infrabuccal ganglion. 

 B.L. buccal tentacle or lobe. 

 CA. caecum; a portion of the wall has been 

 removed so as to show the ridge between 

 the lobes of the caecum and the hepatic 

 valve. 

 GO. gonad. 

 H. heart. 

 IN. intestine. 



I.S. ink sac. 



L. liver. 



OE. oesophagus. 



PA. pancreas. 



PH. pharynx. 



SA median salivary gland. 



Svl.i lateral salivary gland. 



SI. musculus rotator mandibuli. 



SP.G. splanchnic ganglion. 



ST. stomach. 



I. musculus levator mandibuli. 



PLATE II. 



Fig. 8. Venous system, posterior aspect. 



Fig. 9. Arterial and venous systems, left side. 



GI. gill. 



GO. gonad. 



H. heart. 



P.H. peripheral heart. 

 BL.GD. blood gland. 

 Br.H. branchial heart. 



