1. CATODON. 



207 



a large protuberance on the back, called the 'hunch of the neck' ; 

 immediately behind this, or the shoulders, is the thickest part of the 

 body, which from this point gradually tapers off to the tail ; but it 

 does not become much smaller for about another third of the whole 

 length, when the 'small' or taU commences; and at this point on 

 the back is a large prominence of a pyramidal form, called the hwmp, 

 from which a series of small processes run halfway down the small 

 or tail, constituting what is called the ridge ; the body then contracts 

 so much as to become not thicker than a man's body, and terminates 

 in the jlnlces or tail. The two fluTces constitute a large triangular 

 fin. The chest and belly are narrower than the broadest part of the 

 back, and taper off evenly and beautifully towards the tail, giving a 

 clear run. The depth of the head and body is in all parts, except 

 the taU, greater than the width ; the head, viewed in front, presents 

 a broad, somewhat flattened surface, rounded and contracted above, 

 considerably expanded on the sides, and gradually contracted below, 

 so as in some degree to attain a resemblance to the cutwater of a 

 ship. At the angle formed by the anterior and superior surface on' 

 the left side is placed the single blowhole or nostril, which in the 

 dead animal is a slit or fissure in the form of an S, extending hori- 

 zontally. In the right side of the nose and upper surface of the head 

 is a large, almost triangular-shaped cavity, called the case, which is 

 lined with a beautiful glistening membrane, and covered by a thick 

 layer of muscular fibres and small tendons running in various direc- 

 tions, finally united by common integuments. This cavity is for the 

 purpose of secreting and containing an oUy fluid, which is, after 

 death, converted into a granulated substance of a yellowish colour — 

 the spermaceti. 



Fig. 55. 



Atlas of Catodmi australis, MacLeay. From the Museum at Sydney. 



" Beneath the case and nostril, and projecting beyond the lower 

 jaw, is a thick mass of elastic substance — the junk, which is formed 



