THE NARWAL. 83 



spina marrow runs through all the vertebrae, from 

 the head of the fortieth, but does not penetrate the 

 forty-first. The spinous processes diminish in 

 length from the fifteenth lumbar vertebrae, until it is 

 scarcely perceptible at the nineteenth. Large pro- 

 cesses, attached to two adjoining vertebrae, and aris- 

 ing from the inferior surface of the bodies of the 

 vertebrae, commence between the thirtieth and thir- 

 ty-first, and terminate between the forty-second and 

 forty-third. There are twelve ribs, six true and 

 six false, on each side, which are slender for the 

 size of the animal. The sternum is heart-shaped, 

 with the broadest part anteriorly. Two of the 

 false ribs, on each side, are joined by cartilages to 

 the sixth true rib, the others are detached. 



The narwal, when full grown, measures from 

 thirteen to sixteen feet in length, exclusive of the 

 tusk, and at the thickest part, which is two feet be- 

 hind the fins, the circumference is about eight or 

 nine feet. The part of the body anterior to the fins 

 and head, are paraboloidal; the middle portion of 

 body is almost cylindrical, the posterior portion, to 

 within three or four feet of the tail, is somewhat coni- 

 cal; thence, a ridge commencing both at the back and 

 belly, the section becomes first an ellipse, and then 

 a rhombus at the junction of the tail. The perpen- 

 dicular diameter, at a distance of twelve or fourteen 

 inches from the tail, is about one foot, the transverse 

 diameter is about seven inches. The back and 

 belly ridges, run half way or more across the tail; 



