— 113 — 



jaw in this place occasionally shows a slight, faintly marked swelling, as is 

 rendered in True (6) plate 37 fig. 3 for Mcgaptera nodosa Bntr., and on plate 

 12 fig. 3 for Balaenoptera pliysalus L. (see also our sketch on page 108). 



That this swelling is mostly not visible, is owing to the circumstance 

 that the processus coronoideus does not rise much above the upper bony 

 ridge flanking it, and a thick layer of flesh also contributes to the weakening 

 or total extinction of this elevation. 



But immediately behind this processus coronoideus there follows a de- 

 pression of the bone (see our sketch, page 108), by which in that place the 

 external form of the fleshy lower jaw clearly brings out the posterior outline of 

 this excrescence, so that now all doubts as to its position are solved. See True 

 (6) plate 10 fig. 1 and 2; pi. 15 fig. 1 and 2; pi. 37 figi 1. 



In several of these illustrations it looks as if the inferior maxilla ends 

 immediately behind this excrescence; also in our skeleton viewed from in front 

 (taking up a position about 4 feet beside the centre) this seems to be the 

 cose, because the so-called ascending ramus curves inwards and is therefore 

 invisible from the point of view indicated above: the flutings of the skin in 

 that place accordingly make it evident that the surface layer is free from bone, 

 for the very reason that the posterior branch of the lower maxillary there 

 deviates from the periphery of the body. 



Then also the angle of the mouth presents a slit in a backward and 

 downward direction, as is clearly visible in most of the illustrations afore 

 mentioned. This slit of the lips would obviously not slant in this way if the 

 processus coronoideus were in a more anterior position. Moreover the outward 

 appearance of the corner of the mouth demonstrates the absence of an interior 

 hard bony substructure, which is brought out in the sketch. In True (6) pi. 38 

 fig. 2 we see besides the outline of the lower jaw making itself felt owing to 

 the circumstance that the mass of flesh has subsided from flaccidity. 



Concerning the breadth of the two lower maxillae together, it is ob- 

 viously greatest just in front of the eye, which is clearly discernible in True 

 (6) pi. 15 fig. 1, 2 and 4 and in pi. 14 fig. 7. 



In fig. 2 and 7 the head is couched on the left side, the right hand jaw 

 uppermost, so that the rising back part of the lower mandible, which is 

 bound to sag downwards through its own weight, in spite of this lowering, 

 still shows with clearness how great the distance between the two inferior 

 maxillae must be. 



