BR. J. MUEIE ON THE POEM AND STETJCTUEE OF THE MANATEE. 197 



and 1, 2, 3, separate ossific centres; fo'&fo^, the parietal and occipital fonta- 

 nelles ; 0, orbit ; Mf, mental foramen. 



Fig. 17. Base of the same, additional lettering as follows: — Bs, basisphenoid ; As, ali- 

 sphenoid ; Os, orbito-sphenoid ; PI, palatine ; £o, basioccipital ; Eo, exoc- 

 cipital ; f)n, foramen magnum ; Eus, Eustachian sac ; Sf, sphenoidal foramen ; 

 lof, infraorbital foramen; An, anterior palatine foramen; /, incisor-cavity; 

 Mo, molars in dental sacs. 

 Fig. 18. Mouth view of the partially dissected lower jaw with tongue, larynx, hyoid, 

 and muscles in situ. The dotted lines respectively show the approximate 

 limits of the so-called outer lips (consult fig. 7 &c.). 

 b, bristles on II, lower lip ; sp, spines on Ij), lower mandibular or symphysial pad ; 

 T, tongue ; id, inferior dental foramen ; ce, cEsophagus ; tr, trachea ; Cs, constrictor 

 superior; Cwi, constrictor medius ; iS".^/*, stylo-pharyngeus ; iS^^r+A, stylo-glossus and 

 hyoid. 

 Fig. 19. The palate and portion of the upper lip of the same female Manatee. The 

 dotted lines indicate the contour of the muzzle &c. (see fig. 7). 



td, upper lip partly in outline; up, upper callous pad = inner upper lip; b, bristles; 

 sp, palatine spines ; bh, buccal or inner labial hairs. 



PLATE XXIII. 



Fig. 20. Reduced sketch of the viscera in situ of the young male Manatee. The lower 

 left lobe of the liver is partially dragged out by a hook, the better to expose 

 the natural forward tilt of the great curvature of the stomach. 



!£ IV, first and fourth gastric cavities ; and ///, placed on liver, points to the third semi- 

 spiral appendicular cavity; gl, cardiac gland; sp, spleen; Cce, at root of bifurcate 

 caecum ; r, right, and I, left, duplex lobes of liver ; Gb, gall-bladder ; pe, pericardium ; 

 H, four cavities of heart ; pa, pulmonary artery ; ao, aorta ; u, umbilicus ; p, aper- 

 ture for penis ; a, anus. 



Fig. 21. The compound stomach, sliced open to show cavities and walUstructure. 



OS, oesophagus ; I, first gastric ca^'ity (* and white arrow indicate its upper sacculus) 

 gl, cardiac gland; //, second comual cavity; IV, fourth cavity; d, duodenum 

 1, oesophageal opening into stomach; 2, stylet entering orifice of cardiac gland 

 3, communication between / & /F stomachs; 4 & 5, two stylets passing respectively 

 into the 7/ & i// comual gastric divisions; 6, pyloric orifice; dch and pd, ductus 

 communis choledochus and pancreatic duct, to the orifices of which arrows also 

 point ; m, gizzard-like thickening of muscular coat. 



Fig- 22. Compound stomach, denuded of its serous coat, and exhibiting the direction of 

 the external layer of muscular fibres. Lettering corresponds with fig. 21, 



