Prof. Reid on the Vograarus Islandicus. 469 



The scapular arch is very flexible, rather slender, composed of 

 a fibrous-looking tissue, is united to the skull at one point only 

 — to the mastoid bone, — and is continuous throughout its whole 

 length, so that it presents no traces of division into separate por- 

 tions; About 2i inches from the lower edge of the body, the 

 scapular arch bifurcates, and the two branches diverge and pro- 

 ceed to the lower edge of the body, and are 2 inches apart at 

 their termination. The anterior of these two branches is the 

 stronger, and the pectoral fin is attached to it, a little below the 

 bifurcation. 



Muscular St/stem. — The muscular bundles of the trunk are 

 enveloped in several strong fibrous sheaths, formed by prolonga- 

 tions inwards of the fibrous part of the chorion or true skin, at- 

 tached to the spinal column and to the strong laminse prolonged 

 upwards and downwards along the processes of the spinal column. 

 The muscles of the two sides of the body nearly throughout its 

 whole height, are separated by a very strong fibrous partition 

 extending upwards from the upper part of the bodies of the ver- 

 tebrae along the whole length of the spinous processes, and enve- 

 loping that part of the lower extremities of the interspinous or 

 interneural spines interposed between these processes ; and ex- 

 tending downwards from the lower part of the bodies of the ver- 

 tebrae along the transverse processes and inferior spinous pro- 

 cesses as far as they go, and thence continued onwards to the 

 warty-looking cartilaginous tubercles arranged along the lower 

 edge of the body. In the region of the abdomen this partition 

 divides itself into two parts, forming the fibrous lining of the 

 inner surface of the abdominal walls. Three strong aponeurotic 

 septa are sent inwards from the inner surface of the skin to that 

 part of this central partition placed above the spinal column, 

 and two to that part below it, throughout a great part of its 

 length. Another septum is sent inwards from the skin along 

 the lateral line of the body to the spinal column, which is at- 

 tached along the roots of the transverse processes in the abdo- 

 minal vertebrae, and to the central ridge on the bodies of the 

 caudal vertebrae. There are thus three strong sheaths containing 

 muscular bundles placed between the bodies of all the dorsal and 

 the greater part of the caudal vertebrae and the upper extremities 

 of their superior spinous processes, and two similar sheaths be- 

 tween the bodies of a great part of the caudal vertebrae and the 

 lower extremities of their inferior spinous processes. The space 

 between the uppermost of these sheaths and the superior margin 

 of the body contains the muscular bundles which move the dorsal 

 fin rays, and the space between the lowermost of these sheaths 

 and the inferior margin of the body contains a thin layer of 

 muscular fibres which is attached to the central partition, to 



