ANATOMY OF MEGAPTERA LONGIMANA. 159 



space or by a process of the frontal, and in the direction of the 

 posterior surface, roofing the fore part of the nasal cavity. 



In this Megaptera a triangular spine of the frontals, 3 inches 

 long and at first over 2 in breadth, is fitted into the posterior 

 part of the internasal trough, but sunk so as to continue the 

 trough to the top. The visible surface of this frontal spine is 

 furrowed, the furrows on each side running backwards and in- 

 wards to the mesial suture. No other of these finners has this 

 nasal spine visible on the surface. The trough between the 

 inner borders runs the whole length, on the posterior half 1| 

 inch wide, 2^ deep, narrowing towards the point where the 

 nasals meet as a prominent peak. The superficial surface is 

 very narrow behind, the first inch like the end of a large 

 thumb, 1^ inch broad, rounded at the end and sunk into a 

 smoothly arched recess in the frontal. Then the surface broadens 

 by the rapid rise of the inner border, and thereafter becomes 

 grooved and broader distally ; breadth at the middle, from edge 

 to edge of the surface, 1| inch, increased at the hollow of the 

 free border to 3| inches. On to this point the surface looks 

 more outwards than upwards, the plane of the inner border 

 being about 3 inches higher than that of the outer border. 

 The peak projects fully 2| inches beyond the hollow of the 

 distal border; its very oblique inferior border meets the straight 

 superior border at an angle of 45°, the point a little rounded 

 off. The inferior or nasal surface is, on its posterior half, nearly 

 flat with a slight slope upwards to its fellow; on the anterior 

 half, it is bevelled and grooved, facing forwards and inwards, 

 forming a low arched roof, and joins the superficial surface at 

 the free end, the junction so rounded off that there is no exact 

 border between the two surfaces. In this Megaptera there is a 

 foramen in the nasals large enough to receive a large goose- 

 quill, largest in the right nasal, situated on the anterior surface 

 near the distal border. It is present at about the same place 

 in the right nasal only, in this B. musculus. 



[In B. musculus the proximal end is transverse for | inch close to 

 the middle line, then slopes obliquely outward and forward at an 

 angle of 45°, forming a very jagged articulation with the frontal. 

 This obliquity makes the outer border begin almost 2 inches anterior 

 to the inner. The nasals are at first in close contact and well bevelled 

 up till at about |- inch from the frontal, the internasal trough 



