Prof. Reid on the Vogmarus Islandicus. 459 



course of the bodies of the vertebrse, and runs parallel to the mesial 

 line of the bodies of the vertebrae in that part of the body of the 

 animal occupied by the anterior caudal vertebrae, but on proceed- 

 ing backwards it tends a little downwards, so that for the last 9 

 or 10 inches of its course it lies immediately below the lower edge 

 of the bodies of the last caudal vertebrae, and at its termination 

 meets its fellow of the opposite side at the lower edge of the body. 

 Opposite each vertebra this tissue is thickened, forming a series 

 of small, irregular-shaped, slight elevations lying in the course 

 of the lateral line, from the centre of each of which in the 

 neighbourhood of the tail, but there only, there projected a 

 small, hard, sharp spine curved forwards. Many of these ele- 

 vations have a puckered or stellated appearance. When the 

 colouring matter on the surface is rubbed off, the small tubercles 

 on the surface of the chorion or true skin are brought more di- 

 stinctly into view. These tubercles are small and placed near 

 to each other. From nine t6 fifteen of them may be counted 

 lying in, or nearly in, the same line in a space of an inch in 

 length. They vary from /^ths to gV^i of an inch in length in 

 their longest diameters, and are very slightly elevated above the 

 surface of the chorion. The largest are about /^ths of an inch in 

 length, and /^ths in breadth. The larger are placed in parallel 

 rows, a double row running in the course and nearly through 

 the whole length of each interneural spine*, beginning at the 

 upper edge of the body, and terminating opposite the part where 

 the interneural spines dip downwards between the upper extre- 

 mities of the spinous processes of the vertebrae to be united 

 to them by fibrous tissue. The smaller and much more nume- 

 rous tubercles are about one half the size of the largest, are scat- 

 tered irregularly in the intervals of the double rows and over the 

 rest of the surface of the body. These tubercles differ in their 

 intimate structure from those more prominent ones arranged 

 along the lower edge in the manner to be afterwards described. 



As the varied relative heights, at different parts of the body, 

 of the space between the lateral line and the lower margin of the 

 body, that between the lateral line and the upper extremities of 

 the spinous processes of the vertebrae, and of that between the 

 upper extremities of the spinous processes of the vertebrae and 

 the upper margin of the body or that occupied by that portion 

 of the interneural spines placed above the upper extremities of 



* The term interneural spines applied by Professor Owen to tlie inter- 

 spinous bones is used liere, for the structure referred to is not in this fish 

 composed of osseous tissue as in the osseous fishes, but of cartihaginous and 

 a peculiar tissue, and is in all respects so unlike bone, that 1 feel a great re- 

 luctance to give them the name of bones. No doubt the term ' spine ' is not 

 an appropriate one cither, but it is less incongruous than that of 'bone.' 



