144 DR. J. MURIE ON THE WHITE-BEAKED EOTTLENOSE. 



In reference to the fleshy mass which grasps the vertical por- 

 tion of the larynx, this in Lagenorhynchus, as in other forms, is 

 attached to the basiocciput, inner sides of pterygoid plates, and 

 the floor of the internal nares above the postpalatal plates. At 

 the latter point there is a strong median glistening band. Above 

 this the muscle divides and upwardly encircles each channel of 

 the nares for a considerable way up. The direction of the fibres is 

 completely circular below ; and here they clasp the aryteno-epi- 

 glottic cylinder ; above this they become more spiral, and supe- 

 riorly assume a longitudinal direction. The result of this is that 

 the muscle, as a whole, is an elevator and compressor. 



The arytenoid cartilages project about 0*3 inch higher than the 

 epiglottis ; and they are separate, excepting a small portion at the 

 upper end, which is firmly attached by intervening strong fibrous 

 tissue. 



Among the submucous tissues of the interior of the larynx at 

 the root of the epiglottis, and just in front of what represents the 

 corda vocalis, there appears to be a venous plexus of consider- 

 able thickness. The cylinder is longitudinally three-ribbed and 

 sacculate inferiorly. 



The hyo-epiglottic muscles have the same forward direction and 

 general shape appertaining to the Grampus and Globiceps. Their 

 origin is from the short proximal cartilages of the greater cornua. 

 The fibres, fan-shaped, occcupy 1| inch or thereabouts of the 

 body of the hyoid, and, uniting from opposite sides, run upwards 

 and backwards to the front of the epiglottis, ascending to about 

 its middle. 



The mechanical use of these fleshy planes is evidently to draw 

 forwards the epiglottis ; but, from the position and angle at 

 which they lay on this, they seem hardly to have the effect of 

 dragging the epiglottis and adjoining arytenoid cartilages flat on 

 the surface of the oesophagus. Their true action, therefore, as 

 I conceive, must be to steady these. 



Each lateral half or individual muscle seems equivalent to its 

 opposite in size ; and apparently one cannot have more influence 

 than the other in tractile power. Nevertheless there is a cer- 

 tain difference in the plane of obliquity of their relative po- 

 sitions which would render the greater power to the left moiety. 

 By this unequal disposition of the lines of force the glottis would 

 have more sinistral than dextral inclination, leaving one of the 

 pharyngeal floors wider than the other, and thus, as far as 



