Introduction to Am mal Morphology. 273 



like process, in front, many unequal sucker-like ten- 

 tacles : its fore and hinder openings have sphincter 

 muscles. The front of the head is joined to the buccal 

 region by a narrow pscudo-coUiun. Eight radiating 

 ciliated tentacles surround the mouth, into which two 

 salivary glands, and two, ciliated, glandular, buccal 

 pouches open. The buccal cavity is guarded in front 

 by a valve, and contains an oval, wide radula of 2530 

 joints, each of five plates, the median one-toothed, the 

 inner lateral uncinated, the outer lateral unarmed ; it 

 lies on a tongs-shaped lingual cartilage whose branches 

 are approximated below by one transverse adductor, 

 and divaricated by two sheathing muscles. Two ru- 

 dimental conchiolin-covered pharyngeal jaws oppose 

 radula. The oesophagus is short, the stomach 



/ard-like, receiving the paired bile ducts ; the 

 glandular intestine has a primary neural flexure, and 

 forms three folds under and parallel to the oesophagus, 

 finally passing between the two organs of Bojanus, 

 and through the anal sinus to its termination behind 

 the foot. The liver is large, triangular, of one (Sipho- 

 nodentalium) or two (Dentalium) lobes consisting of 

 caeca lined by large, polygonal, coloured cells. 



There is no heart, but the colourless blood accu- 

 mulates in five, wall-less, lacunary sinuses, anal (the 

 , post-abdominal, buccal, cervical, and pedal, 

 ^-abdominal sinus, it enters an anterior 

 ma; forming a vascular riiiL'", from \vhieh, 



;i the other sinuse>, riehly netted laciin; 

 into the ma loot, which . athing organs, 



the- i in . pair of 



out- , one on .hereby 



. admitted. 



T 



