MR. SIBSON ON THE BLOW-HOLE OF THE PORPOISE. 
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from before backwards to open the canal by relaxing the tendons, 22.23 
(see p. 32). 
No. 24. Fig. 1. Is the tendon of 
No. 24 ^ (fig. 7- Archives of the Royal Society). One of a pair of muscles that, like 
No. 10. fig. 2, arch over and compress the anterior deep sac (2). 
Nos. 25.25. Fig. 1. Oblong cartilages, one to each side of the opening of the deep 
anterior sac (2). 
No. 26. Fig. 1. 27. Fig. 3. The vomer separating the two nasal canals. 
No. 27. Fig. 1. The upper portion of the naso-pharyngeal canal. 
No. 28 c. Fig. 3. The naso-pharyngeal canal into which the mouth of the larynx (35) 
ascends through an opening in the pharynx (34). 
Nos. 28.28 a. 28 b. Fig. 1. Muscular fibres that strengthen the naso-pharyngeal canal 
and the pharynx. 
No. 29. Fig. 1. Muscle that descends to the os hyoides from the palatal bone. 
No. 30. Fig. 1. The anterior part of the pharynx. 
No. 31. Fig. 1. The os hyoides. 
No. 32. Fig. 1. The constrictor of the pharynx. 
No. 33. Fig. 1. The thyroid cartilage. 
No. 34. Fig. 3. The sphincter of the opening in the pharynx, through which the 
larynx communicates with the naso-pharyngeal canal, after passing through 
the pharynx and dividing it into two channels. 
No. 35. Fig. 3. The mouth of the larynx. 
No. 36. Fig. 3. The epiglottis. 
No. 37. Fig. 3. The arytenoid cartilages. 
No. 38. Fig. 3. The thyro-arytenoid muscle. 
No. 39. Fig. 3. The crico-arytenoid muscle. 
Nos. 40.41 (fig. 8. Archives of the Royal Society). Constrictors of the mouth of 
the deep anterior sac. 
