8 Messrs. Hancock and Embleton on the Anatomy o/Eolis. 



horny plate : the muscles from the two sides meet together in 

 front of the tongue^ and are attached to the inferior pointed ex- 

 tremity of the cutting-jaws, PL I. fig. 8_^, PL II. 4 c, PL III. 6 e, 

 blending there with the muscles that rotate the tongue back- 

 wards. On the outer surface of the free part of this cheek-mass, 

 as it may be called, is a thin layer of fibres, PL III. fig. 6/, 

 passing at right angles to the bulk of the muscle, and extending 

 from the lower extremity of the cutting-jaws to the side of the 

 oesophagus. At the inferior border of this thin layer lie the sa- 

 livary glands and duct {a). 



The use of this mass of muscle appears to be that of accom- 

 modating itself to the action of the tongue and assisting it in 

 carrying the food backwards into the oesophagus. May the free 

 edges not be the organs of taste ? 



The whole of the muscular walls of the buccal cavity are lined, 

 and the wedge of the tongue is covered by a strong membrane 

 continuous with that which lines the oesophagus, and which forms 

 one or two distinct folds, PL I. figs. 8 h and 6 h, over the pos- 

 terior part of the tongue below the entrance to the oesophagus, 

 but which does not appear to line the horny plates where they 

 are uncovered by muscle, nor to coat the cutting-jaws, andw^hich 

 consequently is not continuous with the membrane which lines the 

 channel of the mouth. It is most probably a mucous membrane. 

 Lips. — These consist of longitudinal and circular fibres : the 

 longitudinal fibres of the inner lip, PL I. fig. l\b, take their ori- 

 gin from a ridge, PL II. fig. 5 a, on the external surface of the 

 anterior edge of the horny plates, where these become continuous 

 with the cutting-jaws ; the fibres arise all the way from the upper 

 to the under margin of the horny plates, inclosing in an elliptical 

 space the cutting-jaws. With these are blended the circular 

 fibres. 



The lip thus formed is coated on its inner and part of its 

 outer surface by the lining membrane of the channel of the 

 mouth, so that it projects by a free border, PL I. figs. 4 and 6 b 

 and lie, which is wrinkled, into the channel leading to the buccal 

 cavity. This inner lip acts as a sphincter to the orifice of the 

 mouth, and will regulate and assist the approximation of the 

 cutting-jaws ; it will also take an active part in the prehension of 

 aliment, which it will carry backwards to the cutting-blades. 



The outer lips are prolonged into a tube, PL I. fig. 4 e, which 

 is the channel of the mouth ; they inclose the inner lip. Their 

 longitudinal muscular fibres, PL I. fig. 6 i, arise from a ridge, 

 PL II. fig. 5 c, on the sides of the horny plates, immediately be- 

 hind the origin of the longitudinal fibres of the inner lip, and 

 pass forward to be blended with the integuments at the external 



